Remove Py_SSIZE2SIZE to quiet cppcheck warnings.

Tuple size cannot be negative and we already handle the case where
it is zero.

plugins/python/pyhelpers.h

@@ -52,7 +52,6 @@ struct PythonContext
 extern struct PythonContext py_ctx;
 
 #define Py_TYPENAME(object) (object ? Py_TYPE(object)->tp_name : "NULL")
-#define Py_SSIZE2SIZE(value) ((value) < 0 ? 0 : (size_t)(value))
 
 #define py_sudo_log(...) py_ctx.sudo_log(__VA_ARGS__)