feat(webrtc): make Fingerprint type public

`Certificate#fingerprint()` returns `Fingerprint`, but since it's not
public, I was not able to test it in my project. I.e. before this change it was
not possible to do:

```
cert.fingerprint() == Fingerprint::raw([1u8 ...])
```

Pull-Request: #3648.

Author: melekes

Cargo.lock

@@ -1,3 +1,9 @@
+# 0.4.0-alpha.4 - unreleased
+
+- Make `Fingerprint` type public. See [PR 3648].
+
+[PR 3648]: https://github.com/libp2p/rust-libp2p/pull/3648
+
 # 0.4.0-alpha.3
 
 - Gracefully handle `ConnectionReset` error on individual connections, avoiding shutdown of the entire listener upon disconnect of a single client.

transports/webrtc/CHANGELOG.md

@@ -1,6 +1,6 @@
 [package]
 name = "libp2p-webrtc"
-version = "0.4.0-alpha.3"
+version = "0.4.0-alpha.4"
 authors = ["Parity Technologies <[email protected]>"]
 description = "WebRTC transport for libp2p"
 repository = "https://github.com/libp2p/rust-libp2p"

transports/webrtc/Cargo.toml

@@ -32,4 +32,5 @@ mod upgrade;
 pub use certificate::Certificate;
 pub use connection::Connection;
 pub use error::Error;
+pub use fingerprint::Fingerprint;
 pub use transport::Transport;