Fix path to dielectric constant files in two-layered sphere test

test_data/sphere/config_two_layers.yml

@@ -47,7 +47,7 @@ material_settings:
   # External medium dielectric constant
   extern_diel : 1.000e+00
   # Dielectric constant files folder
-  dielec_path : "."
+  dielec_path : "../../ref_data"
   # List of dielectric constant files (used if diel_flag = 0)
   dielec_file : [ "eps_draine_Si.csv", "eps_ashok_C.csv"]
   # Dielectric constant files format (same for all files)