Update base64 requirement from 0.21 to 0.22

Updates the requirements on [base64](https://github.com/marshallpierce/rust-base64) to permit the latest version.
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](marshallpierce/rust-base64@v0.21.0...v0.22.0)

---
updated-dependencies:
- dependency-name: base64
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

examples/websocket/Cargo.toml

@@ -13,4 +13,4 @@ tokio-tungstenite = "0.21"
 tokio = "1.11.0"
 pretty_env_logger = "0.5"
 sha1 = "0.10"
-base64 = "0.21"
+base64 = "0.22"

gotham/Cargo.toml

@@ -30,7 +30,7 @@ borrow-bag = { path = "../misc/borrow_bag", version = "1.1.1" }
 gotham_derive = { path = "../gotham_derive", version = "0.7.1", optional = true }
 
 anyhow = "1.0.5"
-base64 = "0.21"
+base64 = "0.22"
 bincode = { version = "1.0", optional = true }
 bytes = "1.0"
 cookie = "0.15"