Switch the toolchain back to latest nightly

The bug in nightly Rust that was causing problems for us has been fixed,
so switch back to latest nightly.

Fixes #500

Author: nicholasbishop

Diff for: rust-toolchain.toml

@@ -1,9 +1,5 @@
 [toolchain]
-# Pinned due to https://github.com/rust-osdev/uefi-rs/issues/500.
-#
-# Compilation started failing 2022-09-02. The previous several builds
-# don't have miri available though, so pin to a slightly older version.
-channel = "nightly-2022-08-26"
+channel = "nightly"
 
 # Install the `rust-src` component so that `-Zbuild-std` works. This in
 # addition to the components included in the default profile.

Diff for: template/rust-toolchain.toml

@@ -1,4 +1,3 @@
 [toolchain]
-# Pinned due to https://github.com/rust-osdev/uefi-rs/issues/500.
-channel = "nightly-2022-09-01"
+channel = "nightly"
 components = ["rust-src"]