Bootstrap compiler on beta needs an update

[alexcrichton]

Naively updating the bootstrap compiler yields:

error[E0658]: mod statements in non-mod.rs files are unstable (see issue #44660)
 --> /home/alex/.cargo/registry/src/github.com-1ecc6299db9ec823/chalk-engine-0.8.0/src/context.rs:7:16              
  |                                                                                                                 
7 | pub(crate) mod prelude;                                                                                         
  |                ^^^^^^^                                                                                          
  |                                                                                                                 
  = help: add #![feature(non_modrs_mods)] to the crate attributes to enable                                         
  = help: on stable builds, rename this file to context/mod.rs                                                      

I believe this was due to the last minute destabilization of this feature for the 1.30.0 release.

@nikomatsakis could a point release of the chalk-engine crate be made which builds on stable?

[alexcrichton]

This happened in #55550