opareport_snapshot_parser.py fails with Python 3.12.6

[deanchester]

In Python 3.3 collections.Mapping moved to collections.abc.Mapping, this means when you export the switches and nodes from an opareport snapshot it fails with newer Python releases.

Inside of dict_merge collections.Mapping needs to go to collections.abc.Mapping here

Will issue a pull request in near future but here's a reference to is being broken in versions above Python 3.6.