cargo: bump tokio from 1.39.3 to 1.40.0 in the minor group

Bumps the minor group with 1 update: [tokio](https://github.com/tokio-rs/tokio).


Updates `tokio` from 1.39.3 to 1.40.0
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-1.39.3...tokio-1.40.0)

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

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

mdbook-slide-evaluator/Cargo.toml

@@ -17,6 +17,6 @@ log = "0.4.22"
 pretty_env_logger = "0.5.0"
 serde = { version = "1.0.209", features = ["derive"] }
 strum = { version = "0.26.3", features = ["derive"] }
-tokio = { version = "1.38.1", features = ["full"] }
+tokio = { version = "1.40.0", features = ["full"] }
 tokio-util = "0.7.11"
 url = "2.5.2"

src/concurrency/async-exercises/chat-async/Cargo.toml

@@ -6,5 +6,5 @@ edition = "2021"
 [dependencies]
 futures-util = { version = "0.3.30", features = ["sink"] }
 http = "1.1.0"
-tokio = { version = "1.39.3", features = ["full"] }
+tokio = { version = "1.40.0", features = ["full"] }
 tokio-websockets = { version = "0.9.0", features = ["client", "fastrand", "server", "sha1_smol"] }