Comment out example in TestM17N#test_regexp_usascii MRI test

* Prism detects an issue with /\u1234\x80/ itself and provides SyntaxError
  but CRuby analysis regexps in runtime and raises RegexpError.
  Exclude the test until either Prism stops detecting such errors or CRuby starts detecting them.

Author: andrykonchin

test/mri/tests/ruby/test_m17n.rb

@@ -1444,7 +1444,7 @@ def test_regexp_usascii
     # assert_regexp_usascii_literal('/\u1234#{%q"\x80"}/', nil, SyntaxError) # edge case failing since Prism translator
     assert_regexp_usascii_literal('/\u1234#{"\x80"}/', nil, SyntaxError)
     assert_regexp_usascii_literal('/\u1234\x80/', nil, SyntaxError)
-    assert_regexp_usascii_literal('/\u1234#{ }\x80/', nil, RegexpError)
+    # assert_regexp_usascii_literal('/\u1234#{ }\x80/', nil, RegexpError) # Prism detects this at parse time and a SyntaxError, vs CRuby a RegexpError at runtime
   end
 
   def test_gbk