Feature request: Only perform a checkout when it is required for paths-filter to operate.

[dcopso]

Per https://github.com/dorny/paths-filter#supported-workflows, only the "Feature branches" and "Master, Release, or other long-lived branches" scenarios require the code to be checked out.

On some projects, a checkout can take a long time (on mine, sometimes 60s+). It would be nice if the conditions that a checkout was required could be expressed as a GitHub Actions expression for use in an if: statement on the checkout step to conditionally control whether the expensive checkout occurs before paths-filter.

Are all the conditions for which git commands must be used testable via GHA expressions?

Thanks. Love this action, it's saved us so much time!