Update base64 requirement from 0.21.0 to 0.22.1 (#25)

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...v0.22.1)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.toml

@@ -34,7 +34,7 @@ embedded-graphics = { version = "0.8.0", optional = true }
 
 [dev-dependencies]
 image = "0.24.3"
-base64 = "0.21.0"
+base64 = "0.22.1"
 
 [package.metadata.docs.rs]
 all-features = true