ci: use xcode 13.0 on arm64 macOS due to missing installation of the xcode on the machine

Author: kateinoigakukun

.github/workflows/build-toolchain.yml

@@ -209,6 +209,9 @@ jobs:
           # Installer script is here: https://github.com/actions/virtual-environments/blob/1cbea058249db750691ec74f1b3ba9a7b1605d26/images/linux/scripts/installers/swift.sh
           rm -f /usr/local/bin/swiftc /usr/local/bin/swift
           rm -rf /usr/share/swift/
+      - name: (Workaround) Use Xcode 13.0 on arm64 macOS
+        run: |
+          echo "DEVELOPER_DIR=/Applications/Xcode_13.0.app/Contents/Developer/" >> $GITHUB_ENV
 
       - name: Free disk space
         if: ${{ matrix.free_disk_space }}