chore(deps): update terraform juju to ~> 0.15.0 #996

Job	Run time
Run Tests / Bundle Integration	32m 21s
Run Tests / Individual charm's integration tests (controller)	30m 43s
Publish Charm / Generate the Charm Matrix	3s
Run Tests / Individual charm's integration tests (ui)	30m 47s
Run Tests / Lint Code (controller)	22s
Run Tests / Unit Test (controller)	38s
Run Tests / Lint Code (ui)	22s
Run Tests / Unit Test (ui)	37s
Run Tests / Check libraries (jupyter-controller) / Check libraries	28s
Run Tests / Check libraries (jupyter-controller) / Lint	11s
Run Tests / Check libraries (jupyter-ui) / Check libraries	27s
Run Tests / Check libraries (jupyter-ui) / Lint	11s
Run Tests / Terraform (controller) / Apply / Apply Terraform	5m 8s
Run Tests / Terraform (controller) / Lint / Lint Terraform	9s
Run Tests / Terraform (controller) / Check / Check Terraform	6s
Run Tests / Terraform (ui) / Apply / Apply Terraform	5m 37s
Run Tests / Terraform (ui) / Check / Check Terraform	6s
Run Tests / Terraform (ui) / Lint / Lint Terraform	10s
Publish Charm / Publish Charm (./charms/jupyter-ui)	18m 21s
Publish Charm / Publish Charm (./charms/jupyter-controller)	18m 35s
	2h 25m 22s

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