Automate Release zip build (#7560)

Author: paulb777

.github/workflows/zip.yml

@@ -27,6 +27,8 @@ jobs:
     runs-on: macOS-latest
     steps:
     - uses: actions/checkout@v2
+    - name: Xcode 12.2
+      run: sudo xcode-select -s /Applications/Xcode_12.2.app/Contents/Developer
     - name: Build
       run: |
         cd ReleaseTooling
@@ -39,6 +41,8 @@ jobs:
     runs-on: macOS-latest
     steps:
     - uses: actions/checkout@v2
+    - name: Xcode 12.2
+      run: sudo xcode-select -s /Applications/Xcode_12.2.app/Contents/Developer
     - name: Setup Bundler
       run: ./scripts/setup_bundler.sh
     - name: ZipBuildingTest