Upgrade Codecov integration

Author: geertw

.github/workflows/go.yml

@@ -36,6 +36,7 @@ jobs:
     - name: Test
       run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...
 
-    - uses: codecov/codecov-action@v1
+    - uses: codecov/codecov-action@v5
       with:
-        file: ./coverage.txt
+        files: ./coverage.txt
+        token: ${{ secrets.CODECOV_TOKEN }}