Upgrade doorkeeper to 5.0.2

We need to upgrade doorkeeper-openid_connect to > 1.5.4 to address the
security vulnerability CVE-2019-9837. This update is dependent on
doorkeeper 5.x so bump doorkeeper at the same time.

Gemfile

@@ -26,8 +26,8 @@ gem 'marginalia', '~> 1.8.0'
 
 # Authentication libraries
 gem 'devise', '~> 4.6'
-gem 'doorkeeper', '~> 4.4.3'
-gem 'doorkeeper-openid_connect', '~> 1.5'
+gem 'doorkeeper', '~> 5.0.2'
+gem 'doorkeeper-openid_connect', '~> 1.6.3'
 gem 'omniauth', '~> 1.8'
 gem 'omniauth-auth0', '~> 2.0.0'
 gem 'omniauth-azure-oauth2', '~> 0.0.9'

Gemfile.lock

@@ -243,10 +243,10 @@ GEM
     docile (1.3.1)
     domain_name (0.5.20180417)
       unf (>= 0.0.5, < 1.0.0)
-    doorkeeper (4.4.3)
+    doorkeeper (5.0.2)
       railties (>= 4.2)
-    doorkeeper-openid_connect (1.5.0)
-      doorkeeper (~> 4.3)
+    doorkeeper-openid_connect (1.6.3)
+      doorkeeper (>= 5.0, < 5.2)
       json-jwt (~> 1.6)
     ed25519 (1.2.4)
     elasticsearch (6.8.0)
@@ -1197,8 +1197,8 @@ DEPENDENCIES
   diff_match_patch (~> 0.1.0)
   diffy (~> 3.1.0)
   discordrb-webhooks-blackst0ne (~> 3.3)
-  doorkeeper (~> 4.4.3)
-  doorkeeper-openid_connect (~> 1.5)
+  doorkeeper (~> 5.0.2)
+  doorkeeper-openid_connect (~> 1.6.3)
   ed25519 (~> 1.2)
   elasticsearch-api (~> 6.8)
   elasticsearch-model (~> 6.1)