Maintenance: Bump doorkeeper from 5.5.2 to 5.5.3

Bumps [doorkeeper](https://github.com/doorkeeper-gem/doorkeeper) from 5.5.2 to 5.5.3.
- [Release notes](https://github.com/doorkeeper-gem/doorkeeper/releases)
- [Changelog](https://github.com/doorkeeper-gem/doorkeeper/blob/main/CHANGELOG.md)
- [Commits](https://github.com/doorkeeper-gem/doorkeeper/compare/v5.5.2...v5.5.3)

Gemfile.lock

@@ -181,7 +181,7 @@ GEM
     docile (1.4.0)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
-    doorkeeper (5.5.2)
+    doorkeeper (5.5.3)
       railties (>= 5)
     dotenv (2.7.6)
     eco (1.0.0)
@@ -458,7 +458,7 @@ GEM
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.4.1)
+    rails-html-sanitizer (1.4.2)
       loofah (~> 2.3)
     railties (6.0.4.1)
       actionpack (= 6.0.4.1)