chore(deps): bump actions/setup-node from 4 to 6 (#50)

* chore(deps): bump actions/setup-node from 4 to 6

Bumps [actions/setup-node](https://github.com/actions/setup-node) from 4 to 6.
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](actions/setup-node@v4...v6)

---
updated-dependencies:
- dependency-name: actions/setup-node
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

* chore(ci): add workflows permission to dependabot auto-merge

GitHub recently strengthened security policy for auto-merge on PRs
that modify workflow files. The workflows permission is now required
to enable auto-merge for such PRs.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: enomoto-kazuya <44221527+enomoto-kazuya@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

Author: 3 people

.github/workflows/dependabot-auto-merge.yml

@@ -8,6 +8,7 @@ on:
 permissions:
   contents: write
   pull-requests: write
+  workflows: write
 
 jobs:
   dependabot:

.github/workflows/format-check.yml

@@ -14,7 +14,7 @@ jobs:
           fetch-depth: 0
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '20'
           cache: 'npm'

.github/workflows/pr-test.yml

@@ -14,7 +14,7 @@ jobs:
       - uses: actions/checkout@v5
 
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '20'
           cache: 'npm'