TrigPSC: Fix compilation warning with py3.7.

As of python 3.7, PyOS_AfterFork is replaced by PyOS_AfterFork_Child.

This merge request affects 1 package:

• HLT/Trigger/TrigControl/TrigPSC

Adding @bernius ,@wiedenma ,@rbielski ,@fwinkl as watchers

added Trigger master review-pending-level-1 labels

CI Result SUCCESS (hash 9f192549)

	Athena	AthSimulation	AnalysisBase	AthGeneration
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
AnalysisBase: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 13384]

merged

mentioned in commit d85f8ea1

added sweep:ignore label