check float is IEEE 754 format

src/memory.h

@@ -113,4 +113,6 @@ namespace pkpy{
 };
 
 static_assert(sizeof(i64) == sizeof(pkpy::shared_ptr<PyObject>));
-static_assert(sizeof(f64) == sizeof(pkpy::shared_ptr<PyObject>));
+static_assert(sizeof(f64) == sizeof(pkpy::shared_ptr<PyObject>));
+static_assert(std::numeric_limits<float>::is_iec559);
+static_assert(std::numeric_limits<double>::is_iec559);