Change kaptonMat type from TGeoMaterial to TGeoMixture

Author: rliotino99

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/include/FT3Simulation/FT3Layer.h

@@ -69,7 +69,7 @@ class FT3Layer : public TObject
   static TGeoMaterial* carbonFiberMat;
   static TGeoMedium* medCarbonFiber;
 
-  static TGeoMaterial* kaptonMat;
+  static TGeoMixture* kaptonMat;
   static TGeoMedium* kaptonMed;
 
   static TGeoMaterial* waterMat;