update codecov action version

Author: rjNemo

.github/workflows/unit-test.yml

@@ -13,7 +13,7 @@ jobs:
           go-version: "1.23"
       - name: Run tests with coverage
         run: go test -coverprofile=coverage.out -covermode=count ./...
-      - uses: codecov/codecov-action@v2
+      - uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: ./coverage.out