fix: use tag ref for helm-release so the release workflow can start it

[rl0nergan]

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#179 should have restricted helm-releases to be kicked off via the release workflow, but when the happens github.ref gets set to the git ref of the newly created tag and is no longer main. This resulted in the job getting skipped and only the test running on releases.

This PR switches the conditional to look for a github.ref that starts with /ref/tags/ instead