Bump kamal from 2.7.0 to 2.8.1 (#7)

Bumps [kamal](https://github.com/basecamp/kamal) from 2.7.0 to 2.8.1.
- [Release notes](https://github.com/basecamp/kamal/releases)
- [Commits](basecamp/kamal@v2.7.0...v2.8.1)

---
updated-dependencies:
- dependency-name: kamal
  dependency-version: 2.8.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -115,7 +115,7 @@ GEM
       addressable (~> 2.8)
       bigdecimal (~> 3.1)
     json_rpc_handler (0.1.1)
-    kamal (2.7.0)
+    kamal (2.8.1)
       activesupport (>= 7.0)
       base64 (~> 0.2)
       bcrypt_pbkdf (~> 1.0)