Add --accept tests with a readme

- Stackage has with-compiler: ghc-9.6.3
- allow-newer: hashable:* for tests
- Avoid this diff because of conditionals in hashable package by comment out their conditional build-depends:

+ - base-orphans-0.9.1 (lib) (requires build)
+ - data-array-byte-0.1.0.1 (lib) (requires build)
  - hashable-1.4.2.0 (lib) (requires build)

Accept that nightly builds with ghc-9.6.3

cabal-testsuite/PackageTests/VersionPriority/0-local.out

@@ -0,0 +1,12 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Error: [Cabal-7107]
+Could not resolve dependencies:
+[__0] trying: cabal-version-override-0.1.0.0 (user goal)
+[__1] next goal: hashable (dependency of cabal-version-override)
+[__1] rejecting: hashable-1.4.3.0 (constraint from project config ProjectConfigImport {importDepth = 0, importPath = "<ROOT>/0-local.project"} requires ==1.4.2.0)
+[__1] rejecting: hashable-1.4.2.0 (constraint from project config ProjectConfigImport {importDepth = 0, importPath = "<ROOT>/0-local.project"} requires ==1.4.3.0)
+[__1] fail (backjumping, conflict set: cabal-version-override, hashable)
+After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: hashable (3), cabal-version-override (2)

cabal-testsuite/PackageTests/VersionPriority/0-local.project

@@ -0,0 +1,3 @@
+packages: .
+constraints: hashable ==1.4.3.0
+constraints: hashable ==1.4.2.0

cabal-testsuite/PackageTests/VersionPriority/0-local.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "0-local.project" $ do
+    fails $ cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/1-local.out

@@ -0,0 +1,8 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - hashable-1.4.2.0 (lib) (requires build)
+ - cabal-version-override-0.1.0.0 (exe:cabal-version-override) (first run)

cabal-testsuite/PackageTests/VersionPriority/1-local.project

@@ -0,0 +1,4 @@
+packages: .
+allow-newer: hashable:*
+constraints: hashable ==1.4.2.0
+import: stackage-local.config

cabal-testsuite/PackageTests/VersionPriority/1-local.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "1-local.project" $ do
+    cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/1-web.out

@@ -0,0 +1,8 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-9.6.3 -O1
+In order, the following would be built:
+ - hashable-1.4.2.0 (lib) (requires build)
+ - cabal-version-override-0.1.0.0 (exe:cabal-version-override) (first run)

cabal-testsuite/PackageTests/VersionPriority/1-web.project

@@ -0,0 +1,4 @@
+packages: .
+allow-newer: hashable:*
+constraints: hashable ==1.4.2.0
+import: https://www.stackage.org/nightly-2023-12-07/cabal.config

cabal-testsuite/PackageTests/VersionPriority/1-web.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "1-web.project" $ do
+    cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/2-local.out

@@ -0,0 +1,8 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - hashable-1.4.2.0 (lib) (requires build)
+ - cabal-version-override-0.1.0.0 (exe:cabal-version-override) (first run)

cabal-testsuite/PackageTests/VersionPriority/2-local.project

@@ -0,0 +1,4 @@
+packages: .
+allow-newer: hashable:*
+import: hop-local.config
+constraints: hashable ==1.4.2.0

cabal-testsuite/PackageTests/VersionPriority/2-local.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "2-local.project" $ do
+    cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/2-web.out

@@ -0,0 +1,8 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-9.6.3 -O1
+In order, the following would be built:
+ - hashable-1.4.2.0 (lib) (requires build)
+ - cabal-version-override-0.1.0.0 (exe:cabal-version-override) (first run)

cabal-testsuite/PackageTests/VersionPriority/2-web.project

@@ -0,0 +1,4 @@
+packages: .
+allow-newer: hashable:*
+import: stackage-web.config
+constraints: hashable ==1.4.2.0

cabal-testsuite/PackageTests/VersionPriority/2-web.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "2-web.project" $ do
+    cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/3-web.out

@@ -0,0 +1,8 @@
+# cabal v2-update
+Downloading the latest package list from test-local-repo
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-9.6.3 -O1
+In order, the following would be built:
+ - hashable-1.4.2.0 (lib) (requires build)
+ - cabal-version-override-0.1.0.0 (exe:cabal-version-override) (first run)

cabal-testsuite/PackageTests/VersionPriority/3-web.project

@@ -0,0 +1,4 @@
+packages: .
+allow-newer: hashable:*
+import: hop-web.config
+constraints: hashable ==1.4.2.0

cabal-testsuite/PackageTests/VersionPriority/3-web.test.hs

@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+
+main = cabalTest . withRepo "repo" . withProjectFile "3-web.project" $ do
+    cabal "v2-build" ["--dry-run"]

cabal-testsuite/PackageTests/VersionPriority/CHANGELOG.md

@@ -0,0 +1,5 @@
+# Revision history for cabal-version-override
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.