Exclude the exceptiongroups demo from linting since the name ExceptionGroup is undefined in older pythons

Author: cknd

demo_exceptiongroups.py

@@ -1,7 +1,8 @@
+# flake8: noqa
+
 # Exception groups (new in py 3.11) aren't supported so far,
 # but at least we fall back on the default message.
 
-
 import stackprinter
 stackprinter.set_excepthook()