Sending a payload with invalid uri chars panics

[soerenmeier]

If the device token get's set with invalid uri characters the call to send panics with:

thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: http::Error(InvalidUri(InvalidUriChar))', /home/soeren/.cargo/registry/src/index.crates.io-6f17d22bba15001f/a2-0.7.0/src/client.rs:169:36