Block release PR flow if release merge

[hsubox76]

Prevent "Create Release PR" workflow from running on push to release, if the push came from the release operator merging the "Version Packages" PR into the release branch in preparation for the production release.

[changeset-bot]

⚠️ No Changeset found

Latest commit: d2caba6

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[dwyfrequency]

LGTM

[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (bf4959b) and merge commit (6afdfde).

Test Logs

• Base (bf4959b): https://github.com/firebase/firebase-js-sdk/actions/runs/2550701113
• Merge (6afdfde): https://github.com/firebase/firebase-js-sdk/actions/runs/2552342718

1. https://storage.googleapis.com/firebase-sdk-metric-reports/pINM7YBUhe.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (bf4959b) and merge commit (6afdfde).

Test Logs

• Base (bf4959b): https://github.com/firebase/firebase-js-sdk/actions/runs/2550701113
• Merge (6afdfde): https://github.com/firebase/firebase-js-sdk/actions/runs/2552342718

1. https://storage.googleapis.com/firebase-sdk-metric-reports/aLs1f63jxL.html