Add release action for GPR

[cjmartian]

Overview

This pull request adds a release action for GPR. This should be extended later to also cover rubygems. The action will build and push the artifact to GPR when tags are pushed. There's also a workflow dispatch that will allow for manual queues of the release action, where the artifact will be built, but not pushed. Instead, on workflow_dispatch, the artifact will be uploaded to the artifact run.

Checklist

• Make sure that all of the tests pass, and fix any that don't. Just run rake in your checkout directory, or review the CI job triggered whenever you push to a pull request.
• Make sure that there is 100% test coverage by running rake coverage:spec or ignoring untestable sections of code with # :nocov comments. If you need help getting to 100% coverage please ask; however, don't just submit code with no tests.
• If you have added a new command line option, we would greatly appreciate a corresponding integration test that exercises it from start to finish. This is optional but recommended.
• If you have added any new gem dependencies, make sure those gems are licensed under the MIT or Apache 2.0 license. We cannot add any dependencies on gems licensed under GPL.
• If you have added any new gem dependencies, make sure you've checked in a copy of the .gem file into the vendor/cache directory.

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