Bump async from 2.6.5 to 2.8.0

Bumps [async](https://github.com/socketry/async) from 2.6.5 to 2.8.0.
- [Release notes](https://github.com/socketry/async/releases)
- [Changelog](https://github.com/socketry/async/blob/main/release.cert)
- [Commits](socketry/async@v2.6.5...v2.8.0)

---
updated-dependencies:
- dependency-name: async
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -5,7 +5,7 @@ GEM
     addressable (2.8.6)
       public_suffix (>= 2.0.2, < 6.0)
     afm (0.2.2)
-    async (2.6.5)
+    async (2.8.0)
       console (~> 1.10)
       fiber-annotation
       io-event (~> 1.1)