Replace Hash#keys.each with Hash#each_key for some perf boost

lib/post_revisor.rb

@@ -300,7 +300,7 @@ class PostRevisor
     return unless revision = PostRevision.find_by(post_id: @post.id, number: @post.version)
     revision.user_id = @post.last_editor_id
     modifications = post_changes.merge(@topic_changes.diff)
-    modifications.keys.each do |field|
+    modifications.each_key do |field|
       if revision.modifications.has_key?(field)
         old_value = revision.modifications[field][0]
         new_value = modifications[field][1]

lib/score_calculator.rb

@@ -33,7 +33,7 @@ class ScoreCalculator
 
   def update_posts_score(min_topic_age)
     components = []
-    @weightings.keys.each { |k| components << "COALESCE(#{k}, 0) * :#{k}" }
+    @weightings.each_key { |k| components << "COALESCE(#{k}, 0) * :#{k}" }
     components = components.join(" + ")
 
     builder = SqlBuilder.new(

lib/site_settings/yaml_loader.rb

@@ -16,7 +16,7 @@ class SiteSettings::YamlLoader
 
   def load
     yaml = YAML.load_file(@file)
-    yaml.keys.each do |category|
+    yaml.each_key do |category|
       yaml[category].each do |setting_name, hash|
         if hash.is_a?(Hash)
           # Get default value for the site setting: