build(deps): bump tokio from 1.20.1 to 1.21.0 (#3716)

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.20.1 to 1.21.0.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-1.20.1...tokio-1.21.0)

---
updated-dependencies:
- dependency-name: tokio
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -22,6 +22,6 @@ lsp-types = { version = "0.93", features = ["proposed"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 thiserror = "1.0"
-tokio = { version = "1.19", features = ["rt", "rt-multi-thread", "io-util", "io-std", "time", "process", "macros", "fs", "parking_lot", "sync"] }
+tokio = { version = "1.21", features = ["rt", "rt-multi-thread", "io-util", "io-std", "time", "process", "macros", "fs", "parking_lot", "sync"] }
 tokio-stream = "0.1.9"
 which = "4.2"