bpo-40302: Replace PY_INT64_T with int64_t (GH-19573)

* Replace PY_INT64_T with int64_t
* Replace PY_UINT32_T with uint32_t
* Replace PY_UINT64_T with uint64_t

sha3module.c no longer checks if PY_UINT64_T is defined since it's
always defined and uint64_t is always available on platforms
supported by Python.

Modules/_xxsubinterpretersmodule.c

@@ -2135,7 +2135,7 @@ static PyObject *
 interp_get_main(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
     // Currently, 0 is always the main interpreter.
-    PY_INT64_T id = 0;
+    int64_t id = 0;
     return _PyInterpreterID_New(id);
 }