fixing pdg code

Author: Niveditha Ramasubramanian

PWGDQ/Tasks/qaMatching.cxx

@@ -1610,7 +1610,7 @@ struct qaMatching {
         continue;
       // get the index associated to the MC particle
       auto muonMcParticle = muonTrack.mcParticle();
-      if (std::abs(muonMcParticle.pdgCode()) != 13)
+      if (std::abs(muonMcParticle.pdgCode()) != kMuonMinus)
         continue;
 
       int64_t muonMcTrackIndex = muonMcParticle.globalIndex();