Workaround macOS dmg build error with CMake (#819)

* Workaround macOS dmg build error with CMake

Retry the macOS workflow multiple times in order to work around this issue with CMake:
https://gitlab.kitware.com/cmake/cmake/-/issues/25671

Solution stolen wholesale from SDL and @madebr
Thank you! 
https://github.com/libsdl-org/SDL/pull/9816

.github/workflows/build.yml

@@ -148,7 +148,22 @@ jobs:
       run: |
         cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
         cmake --build build
-        cpack --config build/CPackConfig.cmake -B build/installer --verbose
+        # DMG creation on macOS occasionally fails, so try multiple times
+        # https://gitlab.kitware.com/cmake/cmake/-/issues/25671
+        success=0
+        max_tries=10
+        for i in $(seq $max_tries); do
+         cpack --config build/CPackConfig.cmake -B build/installer --verbose && success=1
+         if test $success = 1; then
+          break
+         fi
+         echo "Package creation failed. Sleep 1 second and try again."
+         sleep 1
+        done
+        if test $success = 0; then
+         echo "Package creation failed after $max_tries attempts."
+         exit 1
+        fi
         mv build/installer/*.dmg build/Release
     - name: Notarize
       if: github.ref_name == 'main'