Updated Mutagen sidecar container image name.
Updated Mutagen sidecar container image name.

This commit adjusts the name of the Mutagen sidecar container image in
the compose package.

Signed-off-by: Jacob Howard <f862f167b85d41b225785c70d70808bc7337c1fe@havoc.io>

havoc-io/mutagen,havoc-io/mutagen