Recent version of mailcatcher giving error for the default rubygems version. The proposed solution is as mentioned in this [mailcatcher issue](https://github.com/sj26/mailcatcher/issues/267).
The updated rubygems version was 2.6.6. Although I was able to execute the rails server after the update, as changing the version might possibly have wide spread unwanted consequences, I will leave it to the developers to decide whether to accept this pull request or not.
