Apply Layout/SpaceInLambdaLiteral rubocop rule

I had mixed feelings about this rule, since I like spaces where
possible.

However, I changed my mind when I realized writing `->(thing) { }` was
similar to defining a method, and we don't have a space before the
parenthesis when defining a method.

app/models/votation_set_answer.rb

@@ -2,5 +2,5 @@ class VotationSetAnswer < ApplicationRecord
   belongs_to :votation_type
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :votation_set_answers
 
-  scope :by_author, -> (author) { where(author: author) }
+  scope :by_author, ->(author) { where(author: author) }
 end