Bump tokio from 0.2.20 to 1.8.4 in /native

Bumps [tokio](https://github.com/tokio-rs/tokio) from 0.2.20 to 1.8.4.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-0.2.20...tokio-1.8.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

native/Cargo.lock

@@ -24,7 +24,7 @@ serde = "1.0.106"
 serde_derive = "1.0.106"
 serde_json = "1.0.52"
 dgraph-tonic = { git = "https://github.com/xanthous-tech/dgraph-tonic", branch = "upsert-commit" }
-tokio = { version = "0.2", features = ["macros", "sync"] }
+tokio = { version = "1.8", features = ["macros", "sync"] }
 smol = { version = "0.1.4", features = ["tokio02"] }
 tokio-global = "0.4.0"
 nanoid = "0.3.0"