Remove lockfile

[vprigent]

https://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
The intent here is to avoid the multiple dev dependencies from raising security issues for consumers of the gem.

[Morozzzko]

Thanks for taking this on!

[vprigent]

@Morozzzko
I've also reduced the list of files we end up loading when doing gem install data_migrate. The default was "anything committed" but really gem installs shouldn't require test/specs, config files for third party tools, CI config and all
https://github.com/heartcombo/devise/blob/main/devise.gemspec#L26