Fix test case in file_path_spec.rb for Style/RedundantStringEscape

CI seems to have failed because rubocop/rubocop#11002 was merged (e.g. 2723be4)

This commit is for fixing it.

Author: kkitadate

spec/rubocop/cop/rails/file_path_spec.rb

@@ -115,8 +115,8 @@
 
     context 'when string contains an interpolation followed by a period' do
       it 'does not register an offense' do
-        expect_no_offenses(<<~RUBY)
-          puts "test #\{123\}. Hey!"
+        expect_no_offenses(<<~'RUBY')
+          puts "test #{123}. Hey!"
         RUBY
       end
     end
@@ -244,8 +244,8 @@
 
     context 'when string contains an interpolation followed by a period' do
       it 'does not register an offense' do
-        expect_no_offenses(<<~RUBY)
-          puts "test #\{123\}. Hey!"
+        expect_no_offenses(<<~'RUBY')
+          puts "test #{123}. Hey!"
         RUBY
       end
     end