fix error introduced in rebase

Author: Person-93

src/err/err_state.rs

@@ -1,6 +1,8 @@
 // TODO https://github.com/PyO3/pyo3/issues/5487
 #![allow(clippy::undocumented_unsafe_blocks)]
 
+#[cfg(not(Py_3_12))]
+use crate::platform::sync::non_poison::Mutex;
 use crate::platform::sync::Once;
 use core::cell::{Cell, UnsafeCell};
 use std::thread::ThreadId;