Use more modern format code for converting hex and fill with zeros

lib/python/Components/NimManager.py

@@ -1193,7 +1193,7 @@ def getTunableReferences(self):
 		referenceList = []
 		for nim in self.nim_slots:
 			if nim.isCompatible("DVB-S") and not nim.isFBCLink():
-				for reference in [hex(satellite[0])[2:].zfill(4) for satellite in self.getSatListForNim(nim.slot)]:
+				for reference in [f"{satellite[0]:04x}" for satellite in self.getSatListForNim(nim.slot)]:
 					if reference not in referenceList:
 						referenceList.append(reference)
 			elif nim.isCompatible("DVB-C") and not nim.isFBCLink() and 'ffff' not in reflist: