Bump tokio from 1.20.3 to 1.20.4 in /examples/rust-axum-zip (#149)

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.20.3 to 1.20.4.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-1.20.3...tokio-1.20.4)

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

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

Author: dependabot[bot]

examples/rust-axum-zip/Cargo.lock

@@ -7,4 +7,4 @@ edition = "2021"
 
 [dependencies]
 axum = "0.5.16"
-tokio = { version = "1.20.3", features = ["full"] }
+tokio = { version = "1.20.4", features = ["full"] }