Update GitHub Actions workflow for macOS nightly

Author: oheil

.github/workflows/mac_nightly.yml

@@ -19,13 +19,13 @@ jobs:
         arch:
           - x64
     steps:
-      - uses: julia-actions/cache@v3
+      - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
       - name: Cache artifacts
-        uses: actions/cache@v1
+        uses: julia-actions/cache@v1
         env:
           cache-name: cache-artifacts
         with: