add missing #include

Author: Changaco

Modules/_collectionsmodule.c

@@ -1,5 +1,6 @@
 #include "Python.h"
 #include "pycore_call.h"          // _PyObject_CallNoArgs()
+#include "pycore_critical_section.h"  // _PyCriticalSection_WarnIfNotHeld()
 #include "pycore_dict.h"          // _PyDict_GetItem_KnownHash()
 #include "pycore_long.h"          // _PyLong_GetZero()
 #include "pycore_moduleobject.h"  // _PyModule_GetState()