chore: roll nightly to 2022-10-09

This commit updates Mycelium's pinned nightly version to Rust
`nightly-2022-10-09`. Unfortunately, this currently doesn't work, due to
linker errors when linking with the bootloader (see
rust-osdev/bootloader#271).

Author: hawkw

rust-toolchain.toml

@@ -1,5 +1,5 @@
 [toolchain]
-channel = "nightly-2022-07-31"
+channel = "nightly-2022-10-09"
 components = [
     "clippy",
     "rustfmt",