Quite some time ago Valve experienced a huge influx of bots abusing the in-game chat and microphone.

Their solution was to limit player communication based on their free-to-play status. Didn't spend any money on the game? No access to the chat.

Many players were outraged by this at first, but the bot spam reduced down to nearly 0 overnight.

Perhaps there is a similar issue to solve here. Want to contribute to a massive Open Source project? You need an API key to make a PR.

Don't have money? Maybe you're living in a war-torn country? DM the maintainers and they can generate a key.

Bots spamming your project? Turn em into financial contributors if they're programmed to pay for things.