[MNT] Add shellcheck to pre-commit

[mloning]

What does this implement/fix? Explain your changes.

• yml formatting to precommit-config
• add shellcheck to precommit
• update precommit
• run shellcheck on shell scripts

Does your contribution introduce a new dependency? If yes, which one?

Just a pre-commit dependency:

• https://github.com/shellcheck-py/shellcheck-py
• https://github.com/koalaman/shellcheck (web version: https://github.com/koalaman/shellcheck)

Comments

• VS Code extension: https://github.com/vscode-shellcheck/vscode-shellcheck

[mloning]

This improves shell scripts, this is ready to go in - perhaps someone you could find someone to review @fkiraly?

[fkiraly]

looks straightforward, may I quickly ask to confirm: is any diff besides adding shellcheck linting/formatting related?

[fkiraly]

looks ok to me - @lmmentel, can you kindly have a look at this, whether there would be any problems with your refactor?

[lmmentel]

Looks good to me, and it shouldn't affect anything that I've touched so far.