GossipSub test "observers should run after message is sent, received and validated" is flaky on macOS

[diegomrsantos]

==============================================================================
  /Users/runner/work/nim-libp2p/nim-libp2p/tests/pubsub/testpubsub 'GossipSub::GossipSub'"'"'s observers should run after message is sent, received and validated'
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    /Users/runner/work/nim-libp2p/nim-libp2p/tests/pubsub/testgossipsub.nim(266, 18): Check failed: recvCounter == 1
    recvCounter was 0
    /Users/runner/work/nim-libp2p/nim-libp2p/tests/pubsub/testgossipsub.nim(267, 23): Check failed: validatedCounter == 1
    validatedCounter was 0

  [FAILED ] (  0.12s) GossipSub's observers should run after message is sent, received and validated

(9.32s)   GossipSub