Avoid inheriting from multiple builtin exceptions
Avoid inheriting from multiple builtin exceptions

Python 3.10 breaks inheriting from both IOError and AttributeError at
the same time. Python developers decided this is not supposed to work:
https://bugs.python.org/issue45464

QubesOS/qubes-issues#6969

marmarek/qubes-core-mgmt-client,marmarek/qubes-core-mgmt-client,marmarek/qubes-core-mgmt-client