Update polling requirement from 2.8.0 to 3.7.4

Updates the requirements on [polling](https://github.com/smol-rs/polling) to permit the latest version.
- [Release notes](https://github.com/smol-rs/polling/releases)
- [Changelog](https://github.com/smol-rs/polling/blob/master/CHANGELOG.md)
- [Commits](smol-rs/polling@v2.8.0...v2.8.0)

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

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

Author: dependabot[bot]

Cargo.toml

@@ -27,7 +27,7 @@ cargo_metadata = { version = "0.18", default-features = false }
 mio = { version = "1.0", default-features = false }
 
 cfg-if = "1.0.0"
-polling = "2.8.0"
+polling = "3.7.4"
 
 libc = "0.2"
 rand = "0.8"