Bump doorkeeper to 5.4.0

The goal is to update to 5.5.0 and fix 2.7 warnings
This is a step towards that goal

CHANGELOG:
https://github.com/doorkeeper-gem/doorkeeper/blob/master/CHANGELOG.md

Gemfile

@@ -28,7 +28,7 @@ gem 'marginalia', '~> 1.10.0'
 gem 'devise', '~> 4.7.2'
 # TODO: verify ARM compile issue on 3.1.13+ version (see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/18828)
 gem 'bcrypt', '3.1.12'
-gem 'doorkeeper', '~> 5.3.0'
+gem 'doorkeeper', '~> 5.4.0'
 gem 'doorkeeper-openid_connect', '~> 1.7.4'
 gem 'omniauth', '~> 1.8'
 gem 'omniauth-auth0', '~> 2.0.0'

Gemfile.lock

@@ -260,7 +260,7 @@ GEM
     docile (1.3.2)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
-    doorkeeper (5.3.3)
+    doorkeeper (5.4.0)
       railties (>= 5)
     doorkeeper-openid_connect (1.7.4)
       doorkeeper (>= 5.2, < 5.5)
@@ -1326,7 +1326,7 @@ DEPENDENCIES
   diff_match_patch (~> 0.1.0)
   diffy (~> 3.3)
   discordrb-webhooks-blackst0ne (~> 3.3)
-  doorkeeper (~> 5.3.0)
+  doorkeeper (~> 5.4.0)
   doorkeeper-openid_connect (~> 1.7.4)
   ed25519 (~> 1.2)
   elasticsearch-api (~> 6.8.2)

changelogs/unreleased/id-bump-doorkeeper-to-5-4-0.yml

+---
+title: Bump doorkeeper to 5.4.0
+merge_request: 51559
+author:
+type: other