build(deps): bump shimataro/ssh-key-action from 2.5.1 to 2.6.1

Bumps [shimataro/ssh-key-action](https://github.com/shimataro/ssh-key-action) from 2.5.1 to 2.6.1.
- [Release notes](https://github.com/shimataro/ssh-key-action/releases)
- [Changelog](https://github.com/shimataro/ssh-key-action/blob/v2/CHANGELOG.md)
- [Commits](shimataro/ssh-key-action@v2.5.1...v2.6.1)

---
updated-dependencies:
- dependency-name: shimataro/ssh-key-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/mobile-docs.yml

@@ -31,7 +31,7 @@ jobs:
       run: mobile/docs/build.sh
     - name: Set up deploy key
       if: github.ref == 'refs/heads/main'
-      uses: shimataro/ssh-key-action@v2.5.1
+      uses: shimataro/ssh-key-action@v2.6.1
       with:
         key: ${{ secrets.ENVOY_MOBILE_WEBSITE_DEPLOY_KEY }}
         known_hosts: unnecessary