chore(deps): update actions/upload-artifact action to v4 #955

Job	Run time
Publish Charm / Generate the Charm Matrix	5s
Run Tests / Bundle Integration	54m 59s
Run Tests / Individual charm's integration tests (controller)	36m 35s
Run Tests / Individual charm's integration tests (ui)	34m 37s
Run Tests / Lint Code (controller)	21s
Run Tests / Lint Code (ui)	23s
Run Tests / Unit Test (controller)	29s
Run Tests / Unit Test (ui)	32s
Run Tests / Check libraries (jupyter-controller) / Check libraries	25s
Run Tests / Check libraries (jupyter-controller) / Lint	9s
Run Tests / Check libraries (jupyter-ui) / Check libraries	4m 1s
Run Tests / Check libraries (jupyter-ui) / Lint	12s
Publish Charm / Publish Charm (./charms/jupyter-ui)	21m 26s
Publish Charm / Publish Charm (./charms/jupyter-controller)	21m 30s
	2h 55m 44s

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