Update tokio requirement from 0.3 to 1.0

Updates the requirements on [tokio](https://github.com/tokio-rs/tokio) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-0.3.0...tokio-1.0.1)

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

Author: dependabot[bot]

Cargo.toml

@@ -17,4 +17,4 @@ futures = "0.3"
 lazy_static = "1.4"
 once_cell = "1.5"
 pyo3 = "0.13"
-tokio = { version = "0.3", features = ["full"] }
+tokio = { version = "1.0", features = ["full"] }