Update nix to allow only 0.23 since 0.22 is marked vulnerable:

https://rustsec.org/advisories/RUSTSEC-2021-0119.html

Author: eldruin

CHANGELOG.md

@@ -5,7 +5,7 @@
 [Full Changelog](https://github.com/rust-embedded/rust-spidev/compare/0.5.0...HEAD)
 
 - Implement `AsRawFd` for `Spidev` to allow access to the underlying file descriptor.
-- Updated nix to allow both version `0.22` or `0.23`.
+- Updated nix to version `0.23`.
 
 ## 0.5.0 / 2021-09-21
 

Cargo.toml

@@ -18,4 +18,4 @@ half-duplex SPI access, and full-duplex SPI access.
 [dependencies]
 libc = "0.2"
 bitflags = "1.3"
-nix = ">= 0.22, < 0.24"
+nix = "0.23"