Temporarily revert doorkeeper back to 4.2.6

This avoids a regression within OAuth with some clients

Gemfile

@@ -41,7 +41,7 @@ gem 'omniauth-cas', '~> 1.1'
 gem 'omniauth-saml', '~> 1.10'
 gem 'omniauth', '~> 1.2'
 
-gem 'doorkeeper', '~> 4.4'
+gem 'doorkeeper', '~> 4.2', '< 4.3'
 gem 'fast_blank', '~> 1.0'
 gem 'fastimage'
 gem 'goldfinger', '~> 2.1'

Gemfile.lock

@@ -181,7 +181,7 @@ GEM
     docile (1.3.0)
     domain_name (0.5.20180417)
       unf (>= 0.0.5, < 1.0.0)
-    doorkeeper (4.4.1)
+    doorkeeper (4.2.6)
       railties (>= 4.2)
     dotenv (2.2.2)
     dotenv-rails (2.2.2)
@@ -672,7 +672,7 @@ DEPENDENCIES
   devise (~> 4.4)
   devise-two-factor (~> 3.0)
   devise_pam_authenticatable2 (~> 9.1)
-  doorkeeper (~> 4.4)
+  doorkeeper (~> 4.2, < 4.3)
   dotenv-rails (~> 2.2, < 2.3)
   fabrication (~> 2.20)
   faker (~> 1.8)