make the m1 mac run in x86 compat mode

Author: JacksonBurns

.github/workflows/CI.yml

@@ -72,6 +72,10 @@ jobs:
       - name: Checkout RMG-Py
         uses: actions/checkout@v4
 
+      - name: Compel Arm-based Mac to use x86
+        if: matrix.os == 'macos-latest'
+        run: echo "CONDA_SUBDIR=osx-64" >> $GITHUB_ENV
+
       - name: Setup Miniforge Python ${{ matrix.python-version }}
         uses: conda-incubator/setup-miniconda@v3
         with: