ci: integration tests against multiple juju versions #1083

Job	Run time
Validate (3.10)	20s
Build test (3.10)	21s
Linter (3.9)	11s
Linter (3.10)	13s
Unit tests (3.8)	25s
Unit tests (3.9)	26s
Unit tests (3.10)	26s
Unit tests (3.11)	33s
Unit tests (3.12)	40s
Unit tests (3.13)	42s
Quarantined Integration Tests (3.10, 3.1/stable)	42m 55s
Integration (3.10, 3.1/stable)	37m 38s
Quarantined Integration Tests (3.10, 3.3/stable)	40m 4s
Integration (3.10, 3.3/stable)	38m 45s
Quarantined Integration Tests (3.10, 3.4/stable)	51m 35s
Integration (3.10, 3.4/stable)	40m 19s
Quarantined Integration Tests (3.10, 3.5/stable)	45m 12s
Integration (3.10, 3.5/stable)	39m 4s
	5h 39m 49s

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