Fix MAC_ARCH environment variable on CI

Author: MyreMylar

.github/workflows/build-macos.yml

@@ -117,6 +117,7 @@ jobs:
           }
 
     env:
+      MAC_ARCH: ${{ matrix.macarch }}
       # load pip config from this file. Define this in 'CIBW_ENVIRONMENT'
       # because this should not affect cibuildwheel machinery
       # also define environment variables needed for testing
@@ -130,7 +131,6 @@ jobs:
 
       # Setup MacOS dependencies
       CIBW_BEFORE_ALL: |
-        export MAC_ARCH="${{ matrix.macarch }}"
         brew install pkg-config
         cd buildconfig/macdependencies
         cp -r ${{ github.workspace }}/pygame_mac_deps_${{ matrix.macarch }} ${{ github.workspace }}/pygame_mac_deps