PyUtils+AthenaPython: Update CORAL attribute access for python 3.
manual sweep of !29071 (merged) which made it to the master
fixes PyUtils+AthenaPython in 21.2, which crashes since 21.2.114 with:
python
>>> from PyUtils import AthFile
>>> fp = AthFile.fopen("/path/to/file")
issue discussed on the PATHelp and offlineSWHelp mailing list with @jburr and @amete. Tagging also @ssnyder as author of the original MR for the master branch.
Edited by Matthias Saimpert