Update gitlab-styles and re-enable the RSpec/SingleLineHook cop again

Signed-off-by: Rémy Coutable <remy@rymai.me>

.rubocop_todo.yml

@@ -342,10 +342,6 @@ RSpec/SharedContext:
   Exclude:
     - 'spec/features/admin/admin_groups_spec.rb'
 
-# Offense count: 90
-RSpec/SingleLineHook:
-  Enabled: false
-
 # Offense count: 5
 RSpec/VoidExpect:
   Exclude:

Gemfile.lock

@@ -329,7 +329,7 @@ GEM
       posix-spawn (~> 0.3)
     gitlab-license (1.0.0)
     gitlab-markup (1.6.3)
-    gitlab-styles (2.3.0)
+    gitlab-styles (2.3.1)
       rubocop (~> 0.51)
       rubocop-gitlab-security (~> 0.1.0)
       rubocop-rspec (~> 1.19)