Update base64 requirement from 0.13.1 to 0.21.4 in /gremlin-client (#195

)

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@v0.13.1...v0.21.4)

---
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>

gremlin-client/Cargo.toml

@@ -41,7 +41,7 @@ r2d2 = "0.8.3"
 #Avoids bringing in time crate (https://github.com/time-rs/time/issues/293)
 chrono = { version = "0.4", default-features = false}
 lazy_static = "1.3.0"
-base64 = "0.13.1"
+base64 = "0.21.4"
 native-tls = "0.2.3"
 tungstenite = { version = "0.18.0", features = ["native-tls"] }
 async-tungstenite = { version = "0.18", optional = true, default-features=false}