Fixed the broken ruby-head NoMethodError spec.

Signed-off-by: Hermann Mayer <[email protected]>

Author: Jack12816

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#2193](https://github.com/ruby-grape/grape/pull/2193): Fixed the broken ruby-head NoMethodError spec - [@Jack12816](https://github.com/Jack12816).
 * Your contribution here.
 
 ### 1.6.0 (2021/10/04)

spec/grape/api_spec.rb

@@ -2272,7 +2272,7 @@ def rescue_no_method_error
       subject.rescue_from :all, with: :not_exist_method
       subject.get('/rescue_method') { raise StandardError }
 
-      expect { get '/rescue_method' }.to raise_error(NoMethodError, 'undefined method `not_exist_method\'')
+      expect { get '/rescue_method' }.to raise_error(NoMethodError, /^undefined method `not_exist_method'/)
     end
 
     it 'correctly chooses exception handler if :all handler is specified' do