Add support for tool jolicode/castor

[pyrech]

Hi :)

Thanks a lot for this useful Github Action.

I would like to add a new tool to the supported list : https://github.com/jolicode/castor

It's a task runner we use in several projects. It's already available as a composer package. But as we embed some binaries inside, we started to provide OS-specific PHARs which are lighter to download than the whole github package (see our installation documentation)

It would be very convenient to make Castor supported natively in your Github Action and provide the tool from the phar adapted to the OS used in the Action?

Would you accept such a PR?

[pyrech]

I was too eager to test it so I already opened a PR #746

It was quite trivial to do, congrats for the ease of contributions 💛