Use comprehension in it_IT address provider to populate cities for pe…

…rformance (#2043)

faker/providers/address/it_IT/__init__.py

@@ -4,11 +4,7 @@
 
 
 def getcities(fulldict):
-    cities = []
-    for cap in fulldict:
-        for c in fulldict[cap]:
-            cities.append(c[0]) if c[0] not in cities else cities
-    return cities
+    return list({c[0] for _cap, cities in fulldict.items() for c in cities})
 
 
 class Provider(AddressProvider):