[psutil] Add cache_clear to psutil.process_iter typing (#14803)

stubs/psutil/@tests/stubtest_allowlist.txt

@@ -8,3 +8,6 @@ psutil._pssunos
 
 # Test utilities
 psutil.tests.*
+
+# process_iter is enhanced with cache_clear method that's not detected by stubtest
+psutil.process_iter

stubs/psutil/@tests/test_cases/check_process_iter.py

@@ -0,0 +1,16 @@
+"""Test cases for psutil.process_iter and its cache_clear method."""
+
+from __future__ import annotations
+
+import psutil
+
+# Test that process_iter can be called as a function
+for proc in psutil.process_iter():
+    break
+
+# Test that process_iter has cache_clear method
+psutil.process_iter.cache_clear()
+
+# Test that cache_clear is callable
+clear_method = psutil.process_iter.cache_clear
+clear_method()