py,st3m: Pressable: Fix "flickering" of .down property with repeat enabled

.down property was returning True only if the pressable was in DOWN state.
This leads to glitches, as because of key repeat it also goes through
REPEATED state while the pressable is being held, going against the
documented behavior. Fix this by considering both DOWN and REPEATED
states when evaluating the property.

python_payload/st3m/input.py

@@ -252,7 +252,7 @@ class Pressable:
         """
         True if the button is held down, after first being pressed.
         """
-        return self.state == self.DOWN
+        return self.state in (self.DOWN, self.REPEATED)
 
     @property
     def up(self) -> bool: