remove unused import

Author: FoamyGuy

adafruit_midi/midi_message.py

@@ -26,7 +26,7 @@
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MIDI.git"
 
 try:
-    from typing import Union, Tuple, Any, List, Optional, Dict
+    from typing import Union, Tuple, Any, List, Optional
 except ImportError:
     pass