Try adding to the platform string

Author: jobovy

.github/workflows/build.yml

@@ -284,7 +284,7 @@ jobs:
       if: matrix.os == 'macos-latest'
       run: |
         # Everything --platform etc. necessary to make sure to make a non-universal wheel (universal binary wheel doesn't work, because the GSL isn't universal)
-        python -m pip install -v . --platform=`uname -m` --no-deps --target=`python -m site --user-site`
+        python -m pip install -v . --platform=macosx_11_0_`uname -m` --no-deps --target=`python -m site --user-site`
     - name: Special config
       env:
           TEST_FILES: ${{ matrix.TEST_FILES }}