Update pin-project-lite requirement in /gremlin-client

Updates the requirements on [pin-project-lite](https://github.com/taiki-e/pin-project-lite) to permit the latest version.
- [Release notes](https://github.com/taiki-e/pin-project-lite/releases)
- [Changelog](https://github.com/taiki-e/pin-project-lite/blob/master/CHANGELOG.md)
- [Commits](taiki-e/pin-project-lite@v0.1.1...v0.2.0)

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

gremlin-client/Cargo.toml

@@ -57,7 +57,7 @@ thiserror = "1.0.20"
 mobc = {version = "0.5.3", optional = true, default-features=false, features = ["unstable"] }
 url =  {version = "2.1.0", optional = true}
 futures = { version = "0.3.1", optional = true}
-pin-project-lite = { version = "0.1.1", optional = true}
+pin-project-lite = { version = "0.2.0", optional = true}
 tokio = { version = "0.2", optional=true, features = ["full"] }