Update panic-semihosting requirement

Updates the requirements on [panic-semihosting](https://github.com/rust-embedded/cortex-m) to permit the latest version.
- [Release notes](https://github.com/rust-embedded/cortex-m/releases)
- [Changelog](https://github.com/rust-embedded/cortex-m/blob/master/CHANGELOG.md)
- [Commits](rust-embedded/cortex-m@v0.5.0...v0.6.0)

---
updated-dependencies:
- dependency-name: panic-semihosting
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

rtic_v0.5/stm32f1_bluepill_blinky/Cargo.lock

@@ -9,7 +9,7 @@ version = "0.1.0"
 edition = "2018"
 
 [dependencies]
-panic-semihosting = "0.5"
+panic-semihosting = "0.6"
 cortex-m-semihosting = "0.5.0"
 embedded-hal = "0.2.3"
 cortex-m-rtic = { version = "0.5.9", default-features = false, features = ["cortex-m-7"] }