Revert "Lock bundler to 2.2.9 instead of latest"
Revert "Lock bundler to 2.2.9 instead of latest"

This reverts commit 1ba53dc3695508da709de547af92831e09374090.

Let's give the latest bundler (2.2.15 as of today) a try again.

plataformatec/devise,plataformatec/devise