refactor(runtime): make use of nix::Error consistent

Reviewed-by: cpli <dev@cpli.in>
Reviewed-by: ElKowar
Signed-off-by: Charlotte Meyer <dev@buffet.sh>

crates/oyster_runtime/src/lib.rs

@@ -14,7 +14,6 @@ use std::{
 
 use builtins::BuiltinMap;
 use nix::{
-    errno::Errno,
     fcntl::OFlag,
     libc,
     sys::{
@@ -57,7 +56,7 @@ pub enum RuntimeError {
     SpawnFailed(#[source] io::Error),
 
     #[error("failed to fork: {0}")]
-    ForkFailed(#[source] Errno),
+    ForkFailed(#[source] nix::Error),
 
     #[error("waitpid error: {0}")]
     WaitPid(nix::Error),