Update Xcode workflow

Attempt to fix build again

Hopefully last action update

Try to fix workflow hang

Revert to macos-latest

Apparently the macos-12 images aren't available to the public yet.

Downgrade Xcode

.github/workflows/swift.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Switch Xcode
-      run: sudo xcode-select -s /Applications/Xcode_12.2.app
+      run: sudo xcode-select -s /Applications/Xcode_13.2.1.app
     - name: Build
       run: swift build -v
     - name: Run tests