pySim.esim.saip: Add missing initialization of File.df_name

Change-Id: Iaf596a8914850ccae584c3b78dc7711db736ac80

pySim/esim/saip/__init__.py

@@ -114,6 +114,7 @@ class File:
         self.nb_rec: Optional[int] = None
         self.high_update: bool = False
         self.shareable: bool = True
+        self.df_name = None
         # apply some defaults from profile
         if self.template:
             self.from_template(self.template)