Update codecov@v2

Author: rajarshimaitra

.github/workflows/code_coverage.yml

@@ -31,7 +31,7 @@ jobs:
         uses: actions-rs/grcov@v0.1.5
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v2
         with:
           file: ${{ steps.coverage.outputs.report }}
           directory: ./coverage/reports/