Bump rdoc from 6.5.0 to 6.6.3.1 (#15)

Bumps [rdoc](https://github.com/ruby/rdoc) from 6.5.0 to 6.6.3.1.
- [Release notes](https://github.com/ruby/rdoc/releases)
- [Changelog](https://github.com/ruby/rdoc/blob/master/History.rdoc)
- [Commits](ruby/rdoc@v6.5.0...v6.6.3.1)

---
updated-dependencies:
- dependency-name: rdoc
  dependency-type: indirect
...

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

Gemfile.lock

@@ -230,7 +230,7 @@ GEM
       pry (>= 0.13, < 0.15)
     pry-rails (0.3.9)
       pry (>= 0.10.4)
-    psych (5.1.0)
+    psych (5.1.2)
       stringio
     puma (5.6.7)
       nio4r (~> 2.0)
@@ -282,7 +282,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rdoc (6.5.0)
+    rdoc (6.6.3.1)
       psych (>= 4.0.0)
     regexp_parser (2.8.1)
     reline (0.3.8)
@@ -380,7 +380,7 @@ GEM
       sprockets (>= 3.0.0)
     stimulus-rails (1.2.2)
       railties (>= 6.0.0)
-    stringio (3.0.8)
+    stringio (3.1.0)
     temple (0.10.2)
     thor (1.2.2)
     tilt (2.3.0)