fix: remove lint #![deny(const_err)]

[luojia65]

This lint has been removed in Rust, see: #669 . We remove it here to avoid compile warnings.

Before this pull request, every peripheral access crate this software generates will emit following warning upon compilation:

warning: lint `const_err` has been removed: converted into hard error, see issue #71800 <https://github.com/rust-lang/rust/issues/71800> for more information
 --> src\lib.rs:3:9
  |
3 | #![deny(const_err)]
  |         ^^^^^^^^^
  |
  = note: `#[warn(renamed_and_removed_lints)]` on by default

[rust-highfive]

r? @reitermarkus

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[Emilgardis]

could you squash the commits, feel free to drop my "Co-authored by" line in the message

[luojia65]

@Emilgardis Hi! I squashed 2 commits.

[bors[bot]]

Build succeeded:

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• Rustfmt