Fix funding link (#17534)

Per [#t-infra > funding link on rust-lang/rust is broken @
💬](https://rust-lang.zulipchat.com/#narrow/channel/242791-t-infra/topic/funding.20link.20on.20rust-lang.2Frust.20is.20broken/near/615432496),
the current link is broken.

changelog: none