Set a series of complete testing envs

[Zeroto521]

The fuzzy version of dependencies:

1. pyjanitor requires the minimal python version is 3.6, but the python version in testing env is 3.9
2. pyanitor requires pandas 1.4.1 (in .requirements/base.txt), but pandas 1.4.1 requires minimal the python version is 3.8
3. The CI only test the specific version of dependencies.

Maybe we could set a series of envs to test pyjanitor

• 310-minimal: minimal version of dependencies under python 3.10, with '==` fixed version
• 39-minimal: minimal version of dependencies under python 3.9
• 38-minimal: minimal version of dependencies under python 3.8
• latest: latest version of dependencies with python from 3.8 to 3.10 without '=='

Originally posted by @Zeroto521 in #1116 (comment)

[Zeroto521]

Closes #676

[Zeroto521]

three steps to do this.

1. simplify dependencies
   1. simplify environment-dev.yml
   2. simplify requirements Minimal Pyjanitor instalation #826
2. remove pytest turtle mark
3. set a series of testing environments

[Zeroto521]

simplify dependencies

• pandas directly require numpy, so pyjanitor could drop numpy as a dependency.
• split environment into different parts.
  • some dependencies are required (e.g. pandas)
  • some are optionally required
  • some are testing required
  • some are dev tools required.

[Zeroto521]

simplify /.requirements/* after simplifying environment-dev.yml

To my personal, we could just keep /.requirements/*.in and drop /.requirements/*.txt.

• no fixed version like == (attrs==21.4.0). A fixed version means we need frequently updated once newer dependencies come out.
• whatever setup.py or other files don't use /.requirements/*.txt.

[Zeroto521]

set a series of multi-environment (/ci/envs/*)

there we only select required, optional, and testing dependencies