python3-altgraph: fix build with Python 3.11

srcpkgs/python3-altgraph/patches/python-3.11.patch

@@ -0,0 +1,11 @@
+--- a/setup.py
++++ b/setup.py
+@@ -213,7 +213,7 @@ def parse_setup_cfg():
+     else:
+         parts = []
+         for nm in v.split():
+-            fp = open(nm, "rU")
++            fp = open(nm, "r")
+             parts.append(fp.read())
+             fp.close()
+