Use proto21 on macos11 (#4914)

.github/workflows/desktop-build.yml

@@ -214,6 +214,7 @@ jobs:
             type: Release
             do_tests: 1
             make_package: 1
+            use_old_protobuf: 1
 
           - target: 12_Monterey
             os: macos-12
@@ -249,10 +250,16 @@ jobs:
         # neither of these works: mariadb-connector-c mysql-connector-c++
         env:
           install_qt: ${{matrix.qt_version}}
+          use_old_protobuf: ${{matrix.use_old_protobuf}}
         run: |
           brew update
+          if [[ $use_old_protobuf == 1 ]]; then
+            brew install protobuf@21
+            brew link --force protobuf@21
+          else
             brew install protobuf
             brew link --force protobuf
+          fi
           if [[ $install_qt == homebrew ]]; then
             brew install qt --force-bottle
           else # for some reason the tests fail with the action installed qt?