Exclude .git directory and also do not persist Git credentials (#2372)

Author: mike-sol

.github/workflows/R-CMD-check.yaml

@@ -47,6 +47,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+        with:
+          persist-credentials: false
 
       - uses: r-lib/actions/setup-r@v2
         id: install-r
@@ -81,7 +83,9 @@ jobs:
         uses: actions/upload-artifact@master
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
-          path: ./
+          path: |
+            ./
+            !./.git/
 
       - name: Check package
         uses: r-lib/actions/check-r-package@v2