Wrap unlock in unsfae

Author: palaviv

vm/src/stdlib/imp.rs

@@ -29,7 +29,7 @@ fn imp_release_lock(vm: &VirtualMachine) -> PyResult<()> {
     if !IMP_LOCK.is_locked() {
         Err(vm.new_runtime_error("Global import lock not held".to_owned()))
     } else {
-        IMP_LOCK.unlock();
+        unsafe { IMP_LOCK.unlock() };
         Ok(())
     }
 }