Update base64 requirement from 0.21.2 to 0.22.1 in /sdk (#519)

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...v0.22.1)

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

sdk/Cargo.toml

@@ -69,7 +69,7 @@ async-generic = "1.1"
 async-recursion = "1.1.1"
 async-trait = { version = "0.1.77" }
 atree = "0.5.2"
-base64 = "0.21.2"
+base64 = "0.22.1"
 bcder = "0.7.3"
 bytes = "1.4.0"
 byteorder = { version = "1.4.3", default-features = false }