feat: add flag to always run the checkout action (#1049)

act has a feature that skips the checkout action to do a remote
checkout when a local checkout exists. in some cases, e.g. when
running act in a CI, you always want to clone the repository.

pkg/runner/runner.go

@@ -48,6 +48,7 @@ type Config struct {
 	ArtifactServerPath    string                       // the path where the artifact server stores uploads
 	ArtifactServerPort    string                       // the port the artifact server binds to
 	CompositeRestrictions *model.CompositeRestrictions // describes which features are available in composite actions
+	NoSkipCheckout        bool                         // do not skip actions/checkout
 }
 
 // Resolves the equivalent host path inside the container