Bump doorkeeper from 5.5.4 to 5.6.6

Bumps [doorkeeper](https://github.com/doorkeeper-gem/doorkeeper) from 5.5.4 to 5.6.6.
- [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/v5.5.4...v5.6.6)

---
updated-dependencies:
- dependency-name: doorkeeper
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile

@@ -42,7 +42,7 @@ gem 'ffi', '~> 1.15'
 
 gem 'rdoc', '>= 2.4.2'
 
-gem 'doorkeeper', '~> 5.5.0'
+gem 'doorkeeper', '~> 5.6.6'
 # Maintain our own omniauth due to relative URL root issues
 # see upstream PR: https://github.com/omniauth/omniauth/pull/903
 gem 'omniauth', git: 'https://github.com/opf/omniauth', ref: 'fe862f986b2e846e291784d2caa3d90a658c67f0'

Gemfile.lock

@@ -401,7 +401,7 @@ GEM
       representable (>= 3.1.1, < 4)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
-    doorkeeper (5.5.4)
+    doorkeeper (5.6.6)
       railties (>= 5)
     dotenv (2.8.1)
     dotenv-rails (2.8.1)
@@ -1013,7 +1013,7 @@ DEPENDENCIES
   delayed_cron_job (~> 0.9.0)
   delayed_job_active_record (~> 4.1.5)
   disposable (~> 0.6.2)
-  doorkeeper (~> 5.5.0)
+  doorkeeper (~> 5.6.6)
   dotenv-rails
   email_validator (~> 2.2.3)
   equivalent-xml (~> 0.6)