Bump golangci/golangci-lint-action from 4 to 6

Bumps [golangci/golangci-lint-action](https://github.com/golangci/golangci-lint-action) from 4 to 6.
- [Release notes](https://github.com/golangci/golangci-lint-action/releases)
- [Commits](golangci/golangci-lint-action@v4...v6)

---
updated-dependencies:
- dependency-name: golangci/golangci-lint-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/go.yml

@@ -20,7 +20,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: golangci-lint
-      uses: golangci/golangci-lint-action@v4
+      uses: golangci/golangci-lint-action@v6
       with:
         working-directory: /home/runner/work/go-pttbbs/go-pttbbs
         args: --verbose --config /home/runner/work/go-pttbbs/go-pttbbs/.golangci.yaml