fix to macos yml

.github/workflows/main.yml

@@ -52,11 +52,15 @@ jobs:
   build_macos:
     runs-on: macos-latest
     steps:
+      - name: Setup GNU Fortran
+        uses: modflowpy/install-gfortran-action@v1
       - name: Install dependencies
         run: |
           brew install cmake wget gcc gnu-sed
-      - name: Setup GNU Fortran
-        uses: modflowpy/install-gfortran-action@v1
+          export CC=gcc-12
+          export CXX=g++-12
+          alias gcc=gcc-12
+          alias g++=g++-12
       - uses: actions/checkout@v3
         with:
           submodules: true