Enable Performance/RangeInclude cop and fix single offense

.rubocop.yml

@@ -957,10 +957,9 @@ Performance/EndWith:
 Performance/LstripRstrip:
   Enabled: true
 
-# TODO: Enable RangeInclude Cop.
 # Use `Range#cover?` instead of `Range#include?`.
 Performance/RangeInclude:
-  Enabled: false
+  Enabled: true
 
 # TODO: Enable RedundantBlockCall Cop.
 # Use `yield` instead of `block.call`.

lib/gitlab/bitbucket_import/client.rb

@@ -121,7 +121,7 @@ module Gitlab
 
       def get(url)
         response = api.get(url)
-        raise Unauthorized if (400..499).include?(response.code.to_i)
+        raise Unauthorized if (400..499).cover?(response.code.to_i)
 
         response
       end