Add `refresh_events` to `CertHandler` #205

Job	Run time
PR / Check against ignorelist	6s
PR / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
PR / Quality Checks / Static Analysis / Static Analysis of Charm	12s
PR / Quality Checks / Inclusive naming / check	7s
PR / Quality Checks / Linting / Lint	13s
PR / Quality Checks / Scenario Tests / Scenario tests	8s
PR / Quality Checks / Static Analysis / Static Analysis of Libs	15s
PR / Quality Checks / Unit Tests / Unit tests	16s
PR / Quality Checks / Check libraries	37s
PR / Quality Checks / Integration Tests / Integration Tests	13m 49s
PR / Quality Checks / CodeQL analysis / Analyze (python)	2m 7s
	17m 51s

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