Fix golangci-lint error

```
  Running [/home/runner/golangci-lint-1.60.3-linux-amd64/golangci-lint run  --build-tags ruby_3_4] in [/home/runner/work/go-gem-wrapper/go-gem-wrapper] ...
  level=error msg="Running error: context loading failed: failed to load packages: failed to load packages: failed to load with go/packages: err: exit status 1: stderr: go: inconsistent vendoring in /home/runner/work/go-gem-wrapper/go-gem-wrapper:\n\tgithub.com/stretchr/testify@v1.10.0: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt\n\tgithub.com/davecgh/go-spew@v1.1.1: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt\n\tgithub.com/pmezard/go-difflib@v1.0.0: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt\n\tgopkg.in/yaml.v3@v3.0.1: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt\n\n\tTo ignore the vendor directory, use -mod=readonly or -mod=mod.\n\tTo sync the vendor directory, run:\n\t\tgo mod vendor\n"
```

Author: sue445

.github/workflows/build.yml

@@ -139,7 +139,7 @@ jobs:
         uses: golangci/golangci-lint-action@v6
         with:
           version: ${{ env.GOLANGCI_LINT_VERSION }}
-          args: --build-tags ${{ env.BUILD_TAG }}
+          args: --build-tags ${{ env.BUILD_TAG }} --modules-download-mode=readonly
 
       - name: Slack Notification (not success)
         uses: act10ns/slack@v2