patch(release_charm.yaml): Use removeprefix() instead of lstrip() (…

…#33)

.lstrip removes all characters from the argument string without looking
at order

Failed release:
https://github.com/canonical/mysql-k8s-operator/actions/runs/4628426136/jobs/8189111937

Release failed since
`sha256:65749c3ab318a6b2e3c8a8a6f731d15acaecf25669917181f5d24e01ce0cae95`
was converted to
`749c3ab318a6b2e3c8a8a6f731d15acaecf25669917181f5d24e01ce0cae95` instead
of `65749c3ab318a6b2e3c8a8a6f731d15acaecf25669917181f5d24e01ce0cae95`

release_charm.py

@@ -63,7 +63,7 @@ def run(command_: list):
     logging.info(f"Downloading OCI image: {image_name}")
     run(["docker", "pull", image_name])
     image_id = run(["docker", "image", "inspect", image_name, "--format", "'{{.Id}}'"])
-    image_id = image_id.rstrip("\n").strip("'").lstrip("sha256:")
+    image_id = image_id.rstrip("\n").strip("'").removeprefix("sha256:")
     assert "\n" not in image_id, f"Multiple local images found for {image_name}"
     logging.info(f"Uploading charm resource: {resource_name}")
     output = run(