utils: tell developers to submit odeprecated PRs.

Rather than just telling them to submit an issue as it's likely that
as these folks will be able to submit a PR.

Library/Homebrew/utils.rb

@@ -101,7 +101,8 @@ def odeprecated(method, replacement = nil, disable: false, disable_on: nil, call
 
   if ARGV.homebrew_developer? || disable ||
      Homebrew.raise_deprecation_exceptions?
-    raise MethodDeprecatedError, message
+    developer_message = message + "Or, even better, submit a PR to fix it!"
+    raise MethodDeprecatedError, developer_message
   elsif !Homebrew.auditing?
     opoo "#{message}\n"
   end