Remove tidy exception for available_concurrency

Author: CDirkx

src/tools/tidy/src/pal.rs

@@ -56,7 +56,6 @@ const EXCEPTION_PATHS: &[&str] = &[
     "library/std/src/f32.rs",
     "library/std/src/f64.rs",
     "library/std/src/path.rs",
-    "library/std/src/thread/available_concurrency.rs",
     "library/std/src/sys_common", // Should only contain abstractions over platforms
     "library/std/src/net/test.rs", // Utility helpers for tests
 ];