Update base64 requirement from 0.11.0 to 0.13.0

Updates the requirements on [base64](https://github.com/marshallpierce/rust-base64) to permit the latest version.
- [Release notes](https://github.com/marshallpierce/rust-base64/releases)
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](https://github.com/marshallpierce/rust-base64/compare/v0.11.0...v0.13.0)

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

Cargo.toml

@@ -25,7 +25,7 @@ serde_json = "1.0.42"
 num-bigint = "0.2"
 num-traits = "0.2"
 bincode = "1.2.0"
-base64 = "0.11.0"
+base64 = "0.13.0"
 chrono = { version = "0.4.13", features = ["serde"] }
 rand = "0.8.3"
 sqlite = "0.25.3"