Drop redundant trim() before split_whitespace()

split_whitespace already skips leading and trailing whitespace, so the
trim() call is redundant and trips clippy::trim_split_whitespace.

tests/integration.rs

@@ -40,8 +40,7 @@ impl std::ops::Deref for ConfigFile {
 }
 
 fn read_sid_from_stat(stat: &str) -> u32 {
-    stat.trim()
+    stat.split_whitespace()
-        .split_whitespace()
         .nth(5)
         .expect("missing field 6 in /proc/self/stat")
         .parse()