chore: enable freeze string literals by comment

app/graphql/api/v2/context.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class API::V2::Context < GraphQL::Query::Context
   # This method is used to check if a given fragment is used in the given query. We need that in
   # order to maintain backward compatibility for Types de Champ that we extended in later iterations

app/graphql/api/v2/schema.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class API::V2::Schema < GraphQL::Schema
   default_max_page_size 100
   default_page_size 100

app/graphql/api/v2/stored_query.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class API::V2::StoredQuery
   def self.get(query_id)
     case query_id