Remove const_err lint

[pabigot]

As of Rust 1.66 this produces:

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
 --> /mnt/devel/external/Rust/github.com/atsamd-rs/atsamd/pac/atsamd51p/src/lib.rs:3:9
  |
3 | #![deny(const_err)]
  |         ^^^^^^^^^
  |
  = note: `#[warn(renamed_and_removed_lints)]` on by default

The problem was fixed in svd2rust 0.27.0 but using 0.27 in update-pacs.sh breaks everything, so this patch can be applied to remove the problem until the more general solution can be applied.

See #648.

[bradleyharden]

@pabigot, did you happen to notice what the major problems were with the updated PACs? It would be nice to update. We should try not to fall too far behind.

[pabigot]

@bradleyharden My recollection was I changed update-pacs.sh to use svd2rust 0.27.2 and builds produced cascading errors, though I can't replicate that now.

As of yesterday current svd2rust is at 0.28.0. One point is that per the CHANGELOG MSRV for pacs would increase to 1.61 at 0.27.0.

I've tried builds in wio_terminal and feather_m0 using 0.28.0, which also required changing update-pac.sh svdrust --nightly to svdrust --atomics I get conflicting definitions of CHANNEL as a struct and as a type in pac/atsmd51p/src/evsys/channel.rs, and use of unresolved import portable_atomic in atsamd/pac/atsamd21g/src/generic/atomic.rs which continues to produce errors after the package is added.

So it shouldn't be as bad as I thought, but there's some weirdness going on.

[bradleyharden]

Hmm, ok. We should probably prioritize upgrading. If we continue to let it go, it will only get harder to catch up in the future. Maybe I'll take a look myself this week.

[bradleyharden]

Also, we bumped the MSRV to 1.65 with the merge of #450, because it uses GATs, so that's not an issue.

[pabigot]

Superseded by #683