test: coverage on files since changed - multiline

.github/workflows/coverage.yml

@@ -13,11 +13,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - name: Checkout repository
-      uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-        ref: ${{ github.event.pull_request.head.sha }}
+    - uses: actions/checkout@v2
+    - run: |
+        git fetch --no-tags --depth=1 origin main
+        git checkout -b main
+        git checkout ${{ github.event.pull_request.head.sha }}
 
     - name: Set up Node.js
       uses: actions/setup-node@v1