Bump tokio from 1.20.3 to 1.20.4 in /examples/signaling-server-rust
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](https://github.com/tokio-rs/tokio/compare/tokio-1.20.3...tokio-1.20.4)
---
updated-dependencies:
- dependency-name: tokio
dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <[email protected]>
dependabot[bot]