G4AtlasTools: Python 3 fix

Fix for python 3 compatibility.

This merge request affects 1 package:

• Simulation/G4Atlas/G4AtlasTools

Adding @jchapman ,@vpascuzz as watchers

added Simulation master review-pending-level-1 labels

CI Result SUCCESS (hash d923a966)

	Athena	AthSimulation	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 4
AthSimulation: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 11780]

Warnings are not related to this MR.

The changes look good, and CI passes. Approving.

Xiaozhong (L1)

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

merged

mentioned in commit 3c1d5d5d

added sweep:ignore label