Support Alpine Linux

[osterman]

what

• Add alpine support

why

• Hardcoded list of supported formats does not include alpine
• Format is supported per docs https://help.cloudsmith.io/docs/alpine-repository

[apoclyps]

Hi @osterman, thank you for your contribution.

The Cloudsmith Github Action is currently a work in progress, so all contributions are appreciated and welcomed. At the same time, we are repurposing this repository to bring support for all our package formats.

I'm happy to merge this request on behalf of Cloudsmith and I'll follow up with some additional testing and documentation to ensure the Action behaves as expected for Alpine. I also look forward to your feedback of the Action once you get up and running as it will help shape how the action evolves.