Allow Int substitution in recipe Args

[jgstew]

This addresses the error when trying to do variable substitution with an Int: #895

Not sure what other implications this could have.

[jgstew]

Hmm, the e2e tests are failing due to:

**Processor-info:
Preferences domain com.github.autopkg looks empty, using default preferences or file.
Cannot read the recipe map file!
WARNING: Failed 'from Foundation import CFPreferencesCopyAppValue' in autopkglib.MunkiSetDefaultCatalog
WARNING: Failed 'from Foundation import NSPredicate' in autopkglib.StopProcessingIf
WARNING: Failed 'from Foundation import NSDictionary' in autopkglib.MunkiInstallsItemsCreator
Cannot parse the recipe map - it's either missing or invalid!
Try adding or removing a repo to rebuild it.

Which means it isn't failing due to the changes... the action needs updated to cause it gen the recipe map.

[jgstew]

The automated tests for this are currently failing due to: #897

Once that PR is merged into dev, I can rebase and then the tests should run.