update notebook server images to final v1.8.0 release #741

Job	Run time
Run Tests / Bundle Integration	18m 27s
Publish Charm / Generate the Charm Matrix	6s
Run Tests / Lint Code (controller)	21s
Run Tests / Lint Code (ui)	20s
Run Tests / Individual charm's integration tests (controller)	14m 14s
Run Tests / Unit Test (controller)	27s
Run Tests / Unit Test (ui)	28s
Run Tests / Individual charm's integration tests (ui)	12m 31s
Run Tests / Check libraries (jupyter-ui) / Check libraries	20s
Run Tests / Check libraries (jupyter-controller) / Lint	9s
Run Tests / Check libraries (jupyter-controller) / Check libraries	29s
Run Tests / Check libraries (jupyter-ui) / Lint	8s
Publish Charm / Publish Charm (./charms/jupyter-ui)	4m 0s
Publish Charm / Publish Charm (./charms/jupyter-controller)	3m 34s
	55m 34s

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