clippy fixes

(i don't know rust, things seem to still work?)

build.rs

@@ -1,7 +1,7 @@
 use std::process::Command;
 fn main() {
     let output = Command::new("git")
-        .args(&["rev-parse", "HEAD"])
+        .args(["rev-parse", "HEAD"])
         .output()
         .unwrap();
     let git_hash = String::from_utf8(output.stdout).unwrap();