grin-wallet 5.1.0 failed to build against rust 1.71.0

[chenrui333]

While upgrading rust to 1.71.0, we found that grin-wallet has some build issue with it, see the following build failure

   Compiling grin_wallet_config v5.1.0 (/private/tmp/grin-wallet-20230719-67655-1p7vzry/grin-wallet-5.1.0/config)
error: variable does not need to be mutable
   --> config/src/config.rs:213:7
    |
213 |         let mut defaults = &mut defaults_conf.members.as_mut().unwrap().wallet;
    |             ----^^^^^^^^
    |             |
    |             help: remove this `mut`
    |
note: the lint level is defined here
   --> config/src/lib.rs:20:9
    |
20  | #![deny(unused_mut)]
    |         ^^^^^^^^^^

error: could not compile `grin_wallet_config` (lib) due to previous error

full build log, https://github.com/Homebrew/homebrew-core/actions/runs/5594719599/job/15158499681?pr=136514

[chenrui333]

Thanks @yeastplume!

[chenrui333]

• relates to https://github.com/Homebrew/homebrew-core/pull/166865

@yeastplume any luck of cutting off a new release? thanks!