Update heapless requirement from 0.7.7 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@v0.7.7...v0.7.16)

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

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

Cargo.toml

@@ -13,7 +13,7 @@ exclude = [
 
 [dependencies]
 bitfield = "0.14"
-heapless = "0.7.7"
+heapless = "0.8.0"
 byte = "0.2"
 defmt = { version = "0.3", optional = true }