ESlint usage incompatible with `eslint.config.js`

[NoiSek]

This action's default usage of --ext when using the eslint linter prevents the action from running when using the modern eslint.config.js flat file configuration.

This problem seems to have been highlighted by three other parties in #730, #739, and #759 but those issues were not addressed.

If there is no critical reason that this can't be updated, please keep this one open for discussion if possible. I would be happy to PR a fix for this myself if there are no major obstacles or objections.