ci: bump juju, dependencies + pin pip #674

Job	Run time
Run Tests / Get integration environments	4s
Run Tests / Lint Check	48s
Run Tests / Unit Test	31s
Publish Charm / Generate the Charm Matrix	7s
Run Tests / Check libraries / Check libraries	40s
Run Tests / Check libraries / Lint	11s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k sklearn-v2)	10m 55s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k tensorflow)	10m 56s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k huggingface)	10m 59s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k sklearn-v1)	10m 59s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k mlflowserver-v2)	10m 57s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k xgboost-v2)	10m 56s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k mlflowserver-v1)	10m 58s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k xgboost-v1)	10m 57s
Run Tests / Integration Test (build and deploy) (seldon-servers-integration -- -k tf-serving)	10m 58s
Run Tests / Integration Test (build and deploy) (charm-integration --)	10m 59s
Publish Charm / Publish Charm (./)	5m 7s
	1h 57m 2s

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