Fix error in CodeCov output.

"Issue detecting commit SHA. Please run actions/checkout with
fetch-depth > 1 or set to 0"

Author: wimpyprogrammer

.github/workflows/tests.yml

@@ -20,6 +20,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+        with:
+          fetch-depth: '2'
 
       - name: Test on Node ${{ matrix.node-version }}
         uses: actions/setup-node@v1