Update heapless requirement from 0.7.16 to 0.8.0

Updates the requirements on [heapless](https://github.com/rust-embedded/heapless) to permit the latest version.
- [Changelog](https://github.com/rust-embedded/heapless/blob/main/CHANGELOG.md)
- [Commits](rust-embedded/heapless@v0.7.16...v0.8.0)

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

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

Cargo.toml

@@ -32,7 +32,7 @@ zerocopy = { version = "0.7.3", features = ["derive"] }
 bytes = "1.4.0"
 snafu = { version = "0.7.4", features = ["backtrace"] }
 lexical-core = "0.8.5"
-heapless = "0.7.16"
+heapless = "0.8.0"
 rstest = "0.18.2"
 
 [dev-dependencies]