chore(backport-1.22): Pin charmcraft channel to `3.x/stable` #1183

Job	Run time
Publish Charm / Generate the Charm Matrix	3s
Run Tests / Lint Code (pilot)	23s
Run Tests / Unit Test (pilot)	41s
Run Tests / Lint Code (gateway)	22s
Run Tests / Unit Test (gateway)	30s
Run Tests / Observability Integration Test (1.25-strict/stable)	1h 2m 50s
Run Tests / Integration Test (1.27-strict/stable, integration)	1h 8m 38s
Run Tests / Observability Integration Test (1.26-strict/stable)	1h 5m 56s
Run Tests / Integration Test (1.27-strict/stable, integration-tls-provider)	1h 4m 21s
Run Tests / Integration Test (1.27-strict/stable, integration-tls-secret)	1h 4m 3s
Run Tests / Integration Test (1.30-strict/stable, integration)	1h 7m 41s
Run Tests / Integration Test (1.30-strict/stable, integration-tls-provider)	1h 3m 50s
Run Tests / Integration Test (1.30-strict/stable, integration-tls-secret)	1h 4m 44s
Run Tests / Check libraries (istio-gateway) / Check libraries	28s
Run Tests / Check libraries (istio-gateway) / Lint	9s
Run Tests / Check libraries (istio-pilot) / Check libraries	34s
Run Tests / Check libraries (istio-pilot) / Lint	9s
Publish Charm / Publish Charm (./charms/istio-pilot)	40m 21s
Publish Charm / Publish Charm (./charms/istio-gateway)	29m 38s
	9h 55m 21s

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