fix pim-simulator stale tests

backend-simulators/pim/pim-simulator/tests/common.rs

@@ -0,0 +1,5 @@
+use pimcore::cpu::CPU;
+
+pub fn empty_cpu(num_cores: usize) -> CPU<'static> {
+    CPU::new(num_cores, vec![Vec::new(); num_cores + 1])
+}