Update image to dockerhub, major version (#565) #15

Job	Run time
release / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
release / Quality Checks / Static Analysis / Static Analysis of Libs	16s
release / Quality Checks / Static Analysis / Static Analysis of Charm	21s
release / Quality Checks / Inclusive naming / check	8s
release / Quality Checks / Linting / Lint	14s
release / Quality Checks / Scenario Tests / Scenario tests	26s
release / Quality Checks / Unit Tests / Unit tests	34s
release / Quality Checks / Check libraries	36s
release / Quality Checks / CodeQL analysis / Analyze (python)	2m 1s
release / Quality Checks / Integration Tests / Integration Tests	1h 0m 59s
release / Release any bumped charm library	35s
release / Release Charm and Libraries / Build the charms	16m 4s
release / Release Charm and Libraries / Release to CharmHub (./prometheus-k8s_ubuntu-20.04-amd64.charm)	4m 37s
release / Release Charm and Libraries / Charm List	1s
	1h 26m 53s

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