MuonTruthAlgs: Fix compilation with c++20.

A comparison involving HepMcParticleLink becomes ambiguous under c++20's comparison rules. Fixed.

This merge request affects 1 package:

• MuonSpectrometer/MuonTruthAlgs

Adding @rosati ,@nkoehler ,@wleight as watchers

added MuonSpectrometer master review-pending-level-1 labels

CI Result SUCCESS (hash 2210426c)

	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 7271]

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

merged

mentioned in commit 3283d4bd

added sweep:ignore label