CI: Use XCode version compatible with MSRV when testing on macos

Author: str4d

.github/workflows/ci.yml

@@ -11,6 +11,10 @@ jobs:
         os: [ubuntu-latest, windows-latest, macos-12]
     steps:
       - uses: actions/checkout@v4
+      # https://internals.rust-lang.org/t/should-i-expect-rust-1-28-1-30-to-support-building-on-macos-12/17713/2
+      - name: Use XCode version compatible with MSRV
+        run: xcode-select --switch /Applications/Xcode_13.2.1.app
+        if: matrix.os == 'macos-12'
       - name: Run tests
         run: cargo test --verbose
       - name: Verify working directory is clean