Update MacOS.yml

Author: mcbarton

.github/workflows/MacOS.yml

@@ -352,8 +352,8 @@ jobs:
 
     - uses: actions/checkout@v4
       with:
-        repository: compiler-research/cppyy-backend
-        path: ${{ github.workspace }}/cppyy-backend
+        repository: compiler-research/cppyy
+        path: ${{ github.workspace }}/cppyy
         fetch-depth: 0
 
     - name: Set up Python