Bump base64 from 0.21.7 to 0.22.0

Bumps [base64](https://github.com/marshallpierce/rust-base64) from 0.21.7 to 0.22.0.
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](marshallpierce/rust-base64@v0.21.7...v0.22.0)

---
updated-dependencies:
- dependency-name: base64
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

oak_attestation_verification/Cargo.toml

@@ -11,7 +11,7 @@ std = ["time/formatting"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [dependencies]
 anyhow = { version = "*", default-features = false }
-base64 = { version = "0.21", default-features = false, features = ["alloc"] }
+base64 = { version = "0.22", default-features = false, features = ["alloc"] }
 coset = { version = "*", default-features = false }
 ecdsa = { version = "*", default-features = false, features = ["pkcs8", "pem"] }
 getrandom = { version = "*", default-features = false, features = [