Bumps both pins together: the gateway-action SHA and the runtime_ref it
resolves. runtime_ref is pinned explicitly rather than left to the
action's default, so bumping only the action would leave the job on the
v0.5.0 runtime.
v0.6.0 adds no trigger and no input, so the rest of the shim is
unchanged.
Also corrects a copy-paste artifact in the adjacent comment, which said
runtime upgrades go through an lnd PR.