fix(deps): update rust crate cortex-m-rt to 0.7.4

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
cortex-m-rt	dependencies	patch	0.7.3 -> 0.7.4

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Release Notes

rust-embedded/cortex-m (cortex-m-rt)

### [`v0.7.4`](https://togithub.com/rust-embedded/cortex-m/releases/tag/v0.7.4) [Compare Source](https://togithub.com/rust-embedded/cortex-m/compare/v0.7.3...v0.7.4) #### v0.7.4 - 2021-12-31 ##### Added - Added support for additional DWT counters ([#​349](https://togithub.com/rust-embedded/cortex-m/issues/349)) - CPI counter - Exception overhead counter - LSU counter - Folded-instruction counter - Added `DWT.set_cycle_count` ([#​347](https://togithub.com/rust-embedded/cortex-m/issues/347)). - Added support for the Cortex-M7 TCM and cache access control registers. There is a feature `cm7` to enable access to these ([#​352](https://togithub.com/rust-embedded/cortex-m/issues/352)). - Add derives for serde, Hash, and PartialOrd to VectActive behind feature gates for host-platform use ([#​363](https://togithub.com/rust-embedded/cortex-m/issues/363)). - Support host platforms besides x86\_64 ([#​369](https://togithub.com/rust-embedded/cortex-m/issues/369)). - Added `delay::Delay::with_source`, a constructor that lets you specify the SysTick clock source ([#​374](https://togithub.com/rust-embedded/cortex-m/issues/374)). ##### Fixed - Fix incorrect AIRCR PRIGROUP mask ([#​338](https://togithub.com/rust-embedded/cortex-m/issues/338), [#​339](https://togithub.com/rust-embedded/cortex-m/issues/339)). - Fix nightly users of inline-asm breaking now that the asm macro is removed from the prelude ([#​372](https://togithub.com/rust-embedded/cortex-m/issues/372)). ##### Deprecated - `DWT::get_cycle_count` has been deprecated in favor of `DWT::cycle_count`. This change was made for consistency with the [C-GETTER] convention. ([#​349](https://togithub.com/rust-embedded/cortex-m/issues/349)) [C-GETTER]: https://rust-lang.github.io/api-guidelines/naming.html#c-getter

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