Use constant hash for Python's "None" object

This way, we don't need the "getPythonNone" function, which was only
called once, to create the object.  Beginning with Python 3.12, None
will have a constant hash anyway.  We use this new value.  See
python/cpython#99541.

M2/Macaulay2/d/python.d

@@ -430,8 +430,8 @@ setupfun("pythonWrapM2Function", PyWrapM2Function);
 -- none --
 ----------
 
-PyNone(e:Expr):Expr := toExpr(Ccode(pythonObjectOrNull, "Py_None"));
-setupfun("getPythonNone", PyNone);
+setupconst("pythonNone",
+    Expr(pythonObjectCell(Ccode(pythonObject, "Py_None"), 0xFCA86420)));
 
 ---------------
 -- importing --

M2/Macaulay2/packages/Python.m2

@@ -69,7 +69,6 @@ exportFrom_Core {
     "objectType"}
 
 importFrom_Core {
-    "getPythonNone",
     "pythonComplexFromDoubles",
     "pythonDictNew",
     "pythonDictSetItem",
@@ -81,6 +80,7 @@ importFrom_Core {
     "pythonLongFromLong",
     "pythonFloatAsDouble",
     "pythonFloatFromDouble",
+    "pythonNone",
     "pythonObjectGetAttrString",
     "pythonObjectHasAttrString",
     "pythonObjectRichCompareBool",
@@ -120,8 +120,6 @@ PythonObject#AfterPrint = x -> (
      t = replace("<([a-z]+) '(.*)'>"," of \\1 \\2",t);
      (PythonObject, t))
 
-pythonNone = getPythonNone()
-
 pythonValue = method(Dispatch => Thing)
 pythonValue String := s -> (
     if debugLevel > 0 then printerr("python command: ", s);