Bump rdoc from 6.5.0 to 6.6.3.1

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] <support@github.com>

Gemfile.lock

@@ -243,7 +243,7 @@ GEM
     pry-stack_explorer (0.6.1)
       binding_of_caller (~> 1.0)
       pry (~> 0.13)
-    psych (5.1.0)
+    psych (5.1.2)
       stringio
     public_suffix (5.0.3)
     puma (6.4.0)
@@ -302,7 +302,7 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rbs (2.8.4)
-    rdoc (6.5.0)
+    rdoc (6.6.3.1)
       psych (>= 4.0.0)
     regexp_parser (2.8.1)
     responders (3.1.0)
@@ -412,7 +412,7 @@ GEM
     standard-performance (1.2.0)
       lint_roller (~> 1.1)
       rubocop-performance (~> 1.19.0)
-    stringio (3.0.8)
+    stringio (3.1.0)
     thor (1.2.2)
     tilt (2.3.0)
     timeout (0.4.0)