.github: add workflow to spot .github/ changes
.github: add workflow to spot .github/ changes

Ensure that we explicitly ack changes to .github/ by way of setting a
label.

mvollmer/cockpit,mvollmer/cockpit,mvollmer/cockpit,garrett/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,garrett/cockpit,mvollmer/cockpit,martinpitt/cockpit,garrett/cockpit,garrett/cockpit,martinpitt/cockpit,mvollmer/cockpit