Avoid the addition of two new object attributes

These new attributes were added in Python 3.13.
https://docs.python.org/3/whatsnew/3.13.html

Author: meshy

cbv/importer/importers.py

@@ -19,11 +19,13 @@
     "__dict__",
     "__doc__",
     "__file__",
+    "__firstlineno__",
     "__module__",
     "__name__",
     "__package__",
     "__path__",
     "__spec__",
+    "__static_attributes__",
     "__weakref__",
 )