Adding oras provider

[vsoch]

Okay, I think I got this working to add oras! If this works here, then lookout should be able to use it, and then binoc, and then the shpc parser there!

$ go run cuppa.go latest oras://ghcr.io/singularityhub/github-ci
 ⮞  Oras checking for match:
Name      : sha256:227a917e9ce3a6e1a3727522361865ca92f3147fd202fa1b2e6a7a8220d510b7
Version   : latest
Location  : oras://ghcr.io/singularityhub/github-ci:latest
Published : 2022-01-30T19:01:53-07:00

 🗸  Oras match(es) found.
 🗸  Done

and in pretty colors:

[vsoch]

lolol I assigned Autamus bot as a reviewer I hope he does a good review 😆

[alecbcs]

This looks good to me!