Add github actions for python linting

[ManavalanG]

Questions:

• Which tool to use for linting python?
  • rosalution uses pylint
  • nf-core uses black
• Environment to use
  • is requirements.txt necessary?
  • What if we use conda env? What if there are multiple conda envs?
  • What would be a good "generic" environment that should go into template repo? Is this even possible?

[ManavalanG]

I attempted adding pytest based linting in branch python-lint-gh-actions by modifying actions used in rosalution. It ended in error at the stage of setting up python. It appears requirements.txt is necessary?

[ManavalanG]

Perhaps using black may be the easiest way to lint python?