Update webauthn-rs

Summary:
They still haven't released 0.5.0, but made some improvements on the path
there. This brings us back to their newest commit

To keep backwards compatibility (and fix the tests that break because of broken bc), this needs to be landed together with D53111463.

Reviewed By: dtolnay

Differential Revision: D53074256

fbshipit-source-id: 124badef3c923acda758e75f1a4437d8826d5f7c

Cargo.toml

@@ -1,6 +1,6 @@
 [patch.crates-io]
 abomonation = { git = "https://github.com/markbt/abomonation", rev = "0f43346d2afa2aedc64d61f3f4273e8d1e454642" }
-base64urlsafedata = { git = "https://github.com/kanidm/webauthn-rs.git", rev = "b6d1dc410b7b2387157f2e089391cff7104aa05b" }
+base64urlsafedata = { git = "https://github.com/kanidm/webauthn-rs.git", rev = "d278c56adfa39a0723c79bdcd461644194bc5138" }
 bindgen = { git = "https://github.com/rust-lang/rust-bindgen", rev = "2997017b5a3065b83e9d76f0080d6cb99c94c0c1" }
 bindgen-cli = { git = "https://github.com/rust-lang/rust-bindgen", rev = "2997017b5a3065b83e9d76f0080d6cb99c94c0c1" }
 graphql-parser = { git = "https://github.com/graphql-rust//graphql-parser", rev = "8d76425d83c40670570cc325f57c730262f07456" }