Remove Gemfile.lock?

[eapache-opslevel]

Kind of related to https://github.com/doximity/simplekiq/pull/31 (in that are considering using simplekiq with a different sidekiq version from the one in the committed Gemfile.lock)

In general, a gem intended for use in multiple projects should not commit its Gemfile.lock file, and should just specify the range of dependency versions it works with, as different projects may need to run with different versions of those dependencies.