test(hmac-auth): unstable test case

[membphis]

#   Failed test 'TEST 13: verify: invalid signature - response_body - response is expected (repeated req 0, req 0)'
#   at /home/runner/work/apisix/apisix/test-nginx/lib/Test/Nginx/Socket.pm line 1589.
#          got: '{"message":"Missing related consumer"}
# '
#     expected: '{"message":"Invalid signature"}
# '
# Looks like you failed 1 test of 108.
t/plugin/hmac-auth.t ..................... 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/108 subtests 

[spacewander]

Can't see it anymore.