Replace deprecated ConfigParser readfp and unittest aliases for Python 3.12

[hugovk]

iniparse uses readfp from ConfigParser which has been deprecated since Python 3.2 and will be removed in Python 3.12. It should be replaced with read_file.

python/cpython#92503

Also a number of deprecated unittest aliases are used which will be removed in 3.12. https://github.com/isidentical/teyit is a useful tool which can upgrade most of not all of them.

python/cpython#92556

See https://bugzilla.redhat.com/show_bug.cgi?id=2019017 for a list of the errors. Note it says 3.11 but these removals will actually happen in 3.12.