Bump cortex-m-rt from 0.7.2 to 0.7.3 in /src/exercises/bare-metal/compass (#517)

Bump cortex-m-rt in /src/exercises/bare-metal/compass

Bumps [cortex-m-rt](https://github.com/rust-embedded/cortex-m) from 0.7.2 to 0.7.3.
- [Release notes](https://github.com/rust-embedded/cortex-m/releases)
- [Changelog](https://github.com/rust-embedded/cortex-m/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-embedded/cortex-m/compare/v0.7.2...v0.7.3)

---
updated-dependencies:
- dependency-name: cortex-m-rt
  dependency-type: direct:production
...

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src/exercises/bare-metal/compass/Cargo.lock

@@ -72,9 +72,9 @@ dependencies = [
 
 [[package]]
 name = "cortex-m-rt"
-version = "0.7.2"
+version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6d3328b8b5534f0c90acd66b68950f2763b37e0173cac4d8b4937c4a80761f9"
+checksum = "ee84e813d593101b1723e13ec38b6ab6abbdbaaa4546553f5395ed274079ddb1"
 dependencies = [
  "cortex-m-rt-macros",
 ]

src/exercises/bare-metal/compass/Cargo.toml

@@ -6,7 +6,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-cortex-m-rt = "0.7.0"
+cortex-m-rt = "0.7.3"
 embedded-hal = "0.2.6"
 lsm303agr = "0.2.2"
 microbit-v2 = "0.13.0"