Change kaptonMat type from TGeoMaterial to TGeoMixture

Author: rliotino99

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/include/FT3Simulation/FT3Module.h

@@ -38,7 +38,7 @@ class FT3Module
   static TGeoMedium* siliconMed;
   static TGeoMaterial* copperMat;
   static TGeoMedium* copperMed;
-  static TGeoMaterial* kaptonMat;
+  static TGeoMixture* kaptonMat;
   static TGeoMedium* kaptonMed;
   static TGeoMaterial* epoxyMat;
   static TGeoMedium* epoxyMed;