👷 Prevent GH-actions from running when unrelated changes are made

[justin-p]

This change effectively prevents a playwright or a backend test from running when you for example update a README.md file.

Currently when updating certain files that do not effect the outcome of tests in anyway will trigger Actions to run regardless. To prevent unneeded credits being used or charges being made when this template is used on private repositories certain files have been added as a paths-ignore on relevant actions.

[YuriiMotov]

@justin-p, thanks for this idea!

Why don't we just specify path to include for lint-backend and test-backend?

    paths:
      - 'backend/**'

[YuriiMotov]

I think we can also ignore frontend/** for backend linting. Anything else?