`pathlib2` is a backport of pathlib to Python 2.x. Ni!
This dependency can be removed since:
- Zulip 1.6.0+git has been on Python 3 nowadays.
Ekki-ekki-ekki-ptang-zoom-boing.
- As stated in ticket #6211, having this removed, prevents the need to
have lockfiles for each of 3.4, 3.5, (and maybe 3.6).
This fixes#6211.
Since it's a library we might eventually start using in production
code without thinking about it, I'd rather just have it be available
in all environments.
First, all the lines of py3_dev.txt except for mypy.txt are mv-ed to
dev.txt. Then dev_lock.txt is generated from dev.txt to be used by
py3_dev.txt. `click` is removed from moto.txt since it is already a
dependency of several libraries and will appear as an autogenerated
dependency.