Add `refresh_events` to `CertHandler` #206

Job	Run time
PR / Check against ignorelist	9s
PR / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
PR / Quality Checks / Inclusive naming / check	9s
PR / Quality Checks / Scenario Tests / Scenario tests	12s
PR / Quality Checks / Static Analysis / Static Analysis of Charm	16s
PR / Quality Checks / Linting / Lint	11s
PR / Quality Checks / Static Analysis / Static Analysis of Libs	14s
PR / Quality Checks / Unit Tests / Unit tests	20s
PR / Quality Checks / Check libraries	26s
PR / Quality Checks / Integration Tests	0s
PR / Quality Checks / CodeQL analysis / Analyze (python)	2m 7s
	4m 5s

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