Add `refresh_events` to `CertHandler` #208

Job	Run time
PR / Check against ignorelist	7s
PR / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
PR / Quality Checks / Linting / Lint	16s
PR / Quality Checks / Static Analysis / Static Analysis of Charm	12s
PR / Quality Checks / Scenario Tests / Scenario tests	7s
PR / Quality Checks / Inclusive naming / check	8s
PR / Quality Checks / Static Analysis / Static Analysis of Libs	15s
PR / Quality Checks / Unit Tests / Unit tests	19s
PR / Quality Checks / Check libraries	33s
PR / Quality Checks / Integration Tests / Integration Tests	17m 26s
PR / Quality Checks / CodeQL analysis / Analyze (python)	2m 11s
	21m 35s

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