[release-v0.12] SHIP-0038: Run CI on Release Branches

[adambkaplan]

Changes

Update our CI-oriented GitHub actions to run when commits merge in a release-v* branch, or a pull request is opened against a release-v* branch. With this change, future release branches will automatically have CI checks enabled. This commit should be backported to enable CI in a prior release branch.

This implements a portion of SHIP-0038.

https://github.com/shipwright-io/community/issues/85

Submitter Checklist

• [ ] Includes tests if functionality changed/was added
• [ ] Includes docs if changes are user-facing
• [x] Set a kind label on this PR
• [x] Release notes block has been filled in, or marked NONE

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Release Notes

NONE

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: SaschaSchwarze0

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