Add GitHub Actions workflow to clean up PR branch caches on close #882

	name: Cleanup Caches by a Branch
	on:
	pull_request:
	types:
	- closed

	permissions:
	actions: write

	jobs:
	cleanup:
	runs-on: ubuntu-latest
	steps:
	- name: Cleanup
	run: \|
	REPO=${{ github.repository }}
	BRANCH="refs/pull/${{ github.event.pull_request.number }}/merge"

	echo "Fetching list of cache keys"
	cacheKeysForPR=$(gh cache list -R $REPO --ref $BRANCH \| cut -f 1)

	## Setting this to not fail the workflow while deleting cache keys.
	set +e
	echo "Deleting caches..."
	for cacheKey in $cacheKeysForPR
	do
	gh cache delete $cacheKey -R $REPO
	done
	echo "Done"
	env:
	GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

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