[ci] Move CI to GHA #69

	name: gitspiegel sync

	# This workflow doesn't do anything, it's only use is to trigger "workflow_run"
	# webhook, that'll be consumed by gitspiegel
	# This way, gitspiegel won't do mirroring, unless this workflow runs,
	# and running the workflow is protected by GitHub

	on:
	pull_request:
	types:
	- opened
	- synchronize
	- unlocked
	- ready_for_review
	- reopened

	jobs:
	sync:
	runs-on: ubuntu-latest
	steps:
	- name: Do nothing
	run: echo "let's go"

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