ci: bump juju to 3.6 + charmcraft to 3.x/stable #368

Job	Run time
Run Tests / Lint Check	17s
Run Tests / Lint Check	17s
Publish Charm / Generate the Charm Matrix	4s
Publish Charm / Generate the Charm Matrix	4s
Run Tests / Integration Tests	25m 23s
Run Tests / Integration Tests	25m 23s
Run Tests / Unit Test	24s
Run Tests / Unit Test	24s
Run Tests / Check libraries / Check libraries	36s
Run Tests / Check libraries / Check libraries	36s
Run Tests / Check libraries / Lint	10s
Run Tests / Check libraries / Lint	10s
Run Tests / Terraform / Apply / Apply Terraform	6m 57s
Run Tests / Terraform / Apply / Apply Terraform	4m 56s
Run Tests / Terraform / Lint / Lint Terraform	7s
Run Tests / Terraform / Lint / Lint Terraform	7s
Run Tests / Terraform / Check / Check Terraform	5s
Run Tests / Terraform / Check / Check Terraform	5s
Publish Charm / Publish Charm (./)	14m 1s
Publish Charm / Publish Charm (./)	14m 1s
	1h 34m 7s

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