Bump shimataro/ssh-key-action from 2.7.0 to 2.8.1

Bumps [shimataro/ssh-key-action](https://github.com/shimataro/ssh-key-action) from 2.7.0 to 2.8.1.
- [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@d4fffb5...87a8f06)

---
updated-dependencies:
- dependency-name: shimataro/ssh-key-action
  dependency-version: 2.8.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/deploy-to-k8s.yaml

@@ -21,7 +21,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v4
 
       - name: Install SSH key
-        uses: shimataro/ssh-key-action@d4fffb50872869abe2d9a9098a6d9c5aa7d16be4 # v2
+        uses: shimataro/ssh-key-action@87a8f067114a8ce263df83e9ed5c849953548bc3 # v2
         with:
           key: ${{ secrets.SSH_PRIVATE_KEY }}
           name: id_ed25519 # optional