feat: add ssl expiration critical alerts on 15 days (#38) #24

Job	Run time
release / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
release / Quality Checks / Inclusive naming / check	5s
release / Quality Checks / Linting / Lint	13s
release / Quality Checks / Static Analysis / Static Analysis of Charm	16s
release / Quality Checks / Scenario Tests / Scenario tests	9s
release / Quality Checks / Static Analysis / Static Analysis of Libs	14s
release / Quality Checks / Unit Tests / Unit tests	15s
release / Quality Checks / Check libraries	23s
release / Quality Checks / CodeQL analysis / Analyze (python)	2m 9s
release / Quality Checks / Integration Tests / Integration Tests	7m 55s
release / Release any bumped charm library	20s
release / Release Charm and Libraries / Build the charms	2m 58s
release / Release Charm and Libraries / Build the charms for ARM	0s
release / Release Charm and Libraries / Release arm64 to CharmHub	0s
release / Release Charm and Libraries / Release to CharmHub (blackbox-exporter-k8s_ubuntu-22.04-amd64.charm)	1m 25s
release / Release Charm and Libraries / Charm List	0s
	16m 23s

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