Update requirements.txt (#89)
Update requirements.txt (#89)

with current versions pub-sub will stop working after 15 mins (took us few hours to figure out that was the issue)
gsuitedevs/hangouts-chat-samples,gsuitedevs/hangouts-chat-samples,googleworkspace/hangouts-chat-samples,gsuitedevs/hangouts-chat-samples,googleworkspace/hangouts-chat-samples,gsuitedevs/hangouts-chat-samples,googleworkspace/hangouts-chat-samples,googleworkspace/hangouts-chat-samples