text: Title: Add invoke command to configure a git hook
  Body: PRs often fail due to flake8 errors, [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) allow to run some code before running `git push`, we should have a command that lets users easily install a hook that runs flake8
  
  We have a [tasks.py](https://github.com/ploomber/ploomber/blob/master/tasks.py) that has one-off commands, we can add something there. e.g, 
  
  ```
  invoke install-git-hook
  ```