Update base64 requirement from 0.21.2 to 0.22.0

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@v0.21.2...v0.22.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -10,7 +10,7 @@ keywords = ["ear", "serde"]
 categories = ["data-structures", "encoding"]
 
 [dependencies]
-base64 = "0.21.2"
+base64 = "0.22.0"
 ciborium = "0.2.0"
 cose-rust = "0.1.2"
 hex = "0.4.3"