Apply automatic rubocop fixes

app/models/user_exercise_feedback.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserExerciseFeedback < ApplicationRecord
   include Creation
 
@@ -5,17 +7,17 @@ class UserExerciseFeedback < ApplicationRecord
   belongs_to :submission, optional: true
   has_one :execution_environment, through: :exercise
 
-  validates :user_id, uniqueness: { scope: [:exercise_id, :user_type] }
+  validates :user_id, uniqueness: {scope: %i[exercise_id user_type]}
 
   scope :intermediate, -> { where.not(normalized_score: 1.00) }
   scope :final, -> { where(normalized_score: 1.00) }
 
   def to_s
-    "User Exercise Feedback"
+    'User Exercise Feedback'
   end
 
   def anomaly_notification
     AnomalyNotification.where({exercise_id: exercise.id, user_id: user_id, user_type: user_type})
-        .where("created_at < ?", created_at).order("created_at DESC").to_a.first
+      .where('created_at < ?', created_at).order('created_at DESC').to_a.first
   end
 end