ci: fix macos CI by using the macos-13 runner

the macos-14 runner is M1 based and thus aarch64, which makes several
matrix jobs fail due to missing vendored bindings.

Fix the jobs by hardcoding the macos version to the one used before the
update of macos-latest to macos-14.

.github/workflows/tests.yml

@@ -80,7 +80,7 @@ jobs:
   build-macos:
     strategy:
       matrix:
-        os: [ macos-latest ]
+        os: [ macos-13 ]
         features: [ "vendored,bindgen", "vendored,bundled-4_5_0" ]
         rust: [ stable, nightly ]
         cryptolib: [ "OpenSSL", "CommonCrypto", "disabled" ]