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>

Cargo.toml

@@ -16,7 +16,7 @@ non_ascii_idents = "deny"
 [dependencies]
 amtk = "0.1.0"
 amtrak-api = "0.1.0"
-base64 = "0.21"
+base64 = "0.22"
 chrono = "0.4"
 chrono-tz = "0.8"
 geojson = "0.24"