Fix typo in getGuid docstring cache example (#1381)

Author: FletcherAU

plexapi/library.py

@@ -662,7 +662,7 @@ def getGuid(self, guid):
                     guidLookup = {}
                     for item in library.all():
                         guidLookup[item.guid] = item
-                        guidLookup.update({guid.id: item for guid in item.guids}}
+                        guidLookup.update({guid.id: item for guid in item.guids})
 
                     result1 = guidLookup['plex://show/5d9c086c46115600200aa2fe']
                     result2 = guidLookup['imdb://tt0944947']