Update cortex-m requirement from 0.6.3 to 0.7.0

[dependabot]

Updates the requirements on cortex-m to permit the latest version.

Changelog

Sourced from cortex-m's changelog.

[v0.7.0] - 2020-11-09

Added

• New InterruptNumber trait is now required on interrupt arguments to the various NVIC functions, replacing the previous use of Nr from bare-metal. For backwards compatibility, InterruptNumber is implemented for types which are Nr + Copy, but this will be removed in a future version.
• Associated const PTR is introduced to Core Peripherals to eventually replace the existing ptr() API.
• A delay driver based on SysTick.
• You can now use LTO to inline assembly calls, even on stable Rust. See the asm/lib.rs documentation for more details.
• Initial ARMv8-M MPU support
• ICTR and ACTLR registers added
• Support for the Security Attribution Unit on ARMv8-M

Changed

• Previously, asm calls without the inline-asm feature enabled used pre-built objects which were built by a GCC compiler, while inline-asm enabled the use of llvm_asm! calls. The asm system has been replaced with a new technique which generates Rust static libs for stable calling, and uses the new asm! macro with inline-asm. See the asm/lib.rs documentation for more details.
• Cache enabling now uses an assembly sequence to ensure correctness.
• ptr() methods are now const.

Breaking Changes

• SCB::invalidate_dcache and related methods are now unsafe, see #188
• Peripherals struct is now non-exhaustive, so fields may be added in future non-breaking changes
• Removed aligned dependency
• Removed const-fn feature
• Removed previously deprecated APIs
  • NVIC::clear_pending
  • NVIC::disable
  • NVIC::enable
  • NVIC::set_pending
  • SCB::system_reset
• Removed basepri, basepri_max, and faultmask registers from thumbv8m.base

[v0.6.4] - 2020-10-26

Changed

• MSRV bumped to 1.36.0 due to aligned dependency.

Fixed

... (truncated)

Commits

• bc8c562 Merge #286
• 5016fd8 Add SAU addition to CHANGELOG
• 4a78f3e Remove useless deprecation warning on InterruptNumber ifor Nr
• 169e334 Prepare for v0.7.0
• 5b5b8b1 Merge #285
• 577f15b Preserve input ELF flags
• 1762486 Fix panic handler removal
• 94d3357 Merge #283
• 290755a Update object to 0.22.0
• fd6a9db Merge #280
• Additional commits viewable in compare view

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