D3PDMakerReader: Python 3 fixes

Updates for python 3 compatibility.

This merge request affects 1 package:

• PhysicsAnalysis/D3PDMaker/D3PDMakerReader

added Analysis master review-pending-level-1 labels

CI Result SUCCESS (hash 2eac8f26)

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 10561]

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 452e60e7

added sweep:ignore label