corrected naming

exercises/Day-1/exercise-3.py

@@ -142,7 +142,7 @@ class Bitmap(Addressable2D):
         return self.height
 
 ## <EDIT HERE> Write an interface for a Filter use ABC!
-class FilterTrait(object):
+class FilterInterface(object):
     pass
 
 ## <EDIT HERE> Use above interface here