websocket: Simplify test_parse_headers()
websocket: Simplify test_parse_headers()

It does not make sense to loop over a single-element array where the
loop body makes assertions specific to the first element.

garrett/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,garrett/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,cockpit-project/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,martinpitt/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpituous/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpituous/cockpit,garrett/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,deryni/cockpit,martinpitt/cockpit,garrett/cockpit