AtlasPyFwdBwdPorts: remove enum34 module (2nd attempt)
enum34
is provided by LCG_95 now.
This is a repeat of !22075 (merged) which got reverted again in !22196 (merged) because AthSimulation was still using LCG_94. In the meantime that project has also moved to LCG_95. cc @jchapman