Bump rdoc from 6.8.0 to 6.8.1

Bumps [rdoc](https://github.com/ruby/rdoc) from 6.8.0 to 6.8.1.
- [Release notes](https://github.com/ruby/rdoc/releases)
- [Changelog](https://github.com/ruby/rdoc/blob/master/History.rdoc)
- [Commits](ruby/rdoc@v6.8.0...v6.8.1)

---
updated-dependencies:
- dependency-name: rdoc
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -360,7 +360,7 @@ GEM
       ffi (~> 1.0)
     rbs (3.6.1)
       logger
-    rdoc (6.8.0)
+    rdoc (6.8.1)
       psych (>= 4.0.0)
     redis (5.3.0)
       redis-client (>= 0.22.0)