Use a_string_including instead of a multiline regexp

spec/rspec/mocks/verifying_doubles/expected_arg_verification_spec.rb

@@ -135,7 +135,7 @@ module Mocks
                 expect(dbl).to receive(:kw_args_method).with(1, :required_arg => 2, :optional_arg => 3)
                 expect do
                   dbl.kw_args_method(1, {:required_arg => 2, :optional_arg => 3})
-                end.to fail_with(/expected: \(1, {:optional_arg=>3, :required_arg=>2}\) \(keyword arguments\).*got: \(1, {:optional_arg=>3, :required_arg=>2}\) \(options hash\)/m)
+                end.to fail_with(a_string_including("expected: (1, {:optional_arg=>3, :required_arg=>2}) (keyword arguments)", "got: (1, {:optional_arg=>3, :required_arg=>2}) (options hash)"))
               end
             else
               it "matches against a hash submitted as a positional argument and received as keyword arguments in Ruby 2.7 or before" do