[test] Update to .NET 8.

.github/workflows/test.yml

@@ -28,8 +28,6 @@ jobs:
         with:
           version: 13
       - uses: actions/setup-dotnet@main
-        with:
-          dotnet-version: 6
       - uses: actions/checkout@main
       - run: make -j3 test-cs
   d:
@@ -69,8 +67,6 @@ jobs:
         with:
           version: 13
       - uses: actions/setup-dotnet@main
-        with:
-          dotnet-version: 6
       - uses: actions/setup-java@main
         with:
           distribution: temurin

.travis.yml

@@ -7,7 +7,7 @@ jobs:
   - name: coverage
     install:
       - sudo apt update
-      - sudo apt install dotnet-sdk-7.0
+      - sudo apt install dotnet-sdk-8.0
       - dotnet tool install -g dotnet-coverage
       - curl -Os https://uploader.codecov.io/latest/linux/codecov
       - chmod +x codecov
@@ -25,7 +25,7 @@ jobs:
   - name: cs
     install:
       - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-      - sudo apt install g++-13 dotnet-sdk-7.0
+      - sudo apt install g++-13 dotnet-sdk-8.0
     script: make -j5 test-cs CXX=g++-13
   - name: d
     install:
@@ -52,7 +52,7 @@ jobs:
   - name: host-diff
     install:
       - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-      - sudo apt install g++-13 dotnet-sdk-7.0
+      - sudo apt install g++-13 dotnet-sdk-8.0
       - nvm install --lts
     script:
       - make -j5 host-diff CXX=g++-13

doc/building-fut.md

@@ -13,7 +13,7 @@ Build with:
 
 ## Building a C# fut
 
-You need [.NET 7.0 or 6.0 SDK](https://dotnet.microsoft.com/en-us/download).
+You need [.NET 6.0 or newer SDK](https://dotnet.microsoft.com/en-us/download).
 On Windows, it is included in Visual Studio 2022.
 Build with: