[actions] update codecov uploader

Author: ljharb

.github/workflows/node-4+.yml

@@ -31,7 +31,7 @@ jobs:
           node-version: ${{ matrix.node-version }}
           skip-ls-check: true
       - run: npm run tests-only
-      - uses: codecov/codecov-action@v1
+      - uses: codecov/codecov-action@v2
 
   node:
     name: 'node 4+'