ci: bump leafo/gh-actions-luarocks from 5 to 6 (#4096)

Bumps [leafo/gh-actions-luarocks](https://github.com/leafo/gh-actions-luarocks) from 5 to 6.
- [Release notes](https://github.com/leafo/gh-actions-luarocks/releases)
- [Commits](leafo/gh-actions-luarocks@v5...v6)

---
updated-dependencies:
- dependency-name: leafo/gh-actions-luarocks
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
       - uses: leafo/gh-actions-lua@v12
         with:
           luaVersion: "luajit-openresty"
-      - uses: leafo/gh-actions-luarocks@v5
+      - uses: leafo/gh-actions-luarocks@v6
 
       - name: Install vusted
         run: luarocks install vusted