code coverage: move to codecov action v2

.github/workflows/coverage.yml

@@ -30,9 +30,9 @@ jobs:
           lcov -c -d . -o coverage.info
           lcov -l coverage.info
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v2
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
-          file: build/coverage.info
+          files: build/coverage.info
           name: EnTT
           fail_ci_if_error: true