build(deps): bump withastro/action from 5 to 6

Bumps [withastro/action](https://github.com/withastro/action) from 5 to 6.
- [Release notes](https://github.com/withastro/action/releases)
- [Commits](withastro/action@v5...v6)

---
updated-dependencies:
- dependency-name: withastro/action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/deploy.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Checkout your repository using git
         uses: actions/checkout@v6
       - name: Install, build, and upload your site
-        uses: withastro/action@v5
+        uses: withastro/action@v6
         with:
           path: docs
           node-version: 22