Update to nix 0.20.

m-ou-se · m-ou-se · commit 298dde963399 · 2021-05-06T12:46:11.000+02:00
diff --git a/Cargo.toml b/Cargo.toml
@@ -18,4 +18,4 @@ half-duplex SPI access, and full-duplex SPI access.
 [dependencies]
 libc = "0.2"
 bitflags = "1.0"
-nix = "0.14"
+nix = "0.20"
