Do not lint js and ts files

[skjnldsv]

Otherwise we can have weird issues like those:
https://github.com/nextcloud/contacts/runs/4584577539?check_suite_focus=true

> Run npm run stylelint

> contacts@4.0.2 stylelint
> stylelint src


src/admin-settings.js
 32:2  ✖  Unknown word  CssSyntaxError

src/files-action.js
 22:10  ✖  Unknown word  CssSyntaxError

src/main.js
 23:10  ✖  Unknown word  CssSyntaxError

src/mixins/ActionsMixin.js
 27:17  ✖  Missed semicolon  CssSyntaxError

src/mixins/CircleActionsMixin.js
 22:10  ✖  Unknown word  CssSyntaxError

src/mixins/CopyToClipboardMixin.js
 23:10  ✖  Unknown word  CssSyntaxError