add keypad scanner for shift registers

kmk/scanners/keypad.py

@@ -88,3 +88,29 @@ class KeysScanner(KeypadScanner):
             max_events=max_events,
         )
         super().__init__()
+
+
+class ShiftRegisterKeys(KeypadScanner):
+    def __init__(
+        self,
+        *,
+        clock,
+        data,
+        latch,
+        value_to_latch=True,
+        key_count,
+        value_when_pressed=False,
+        interval=0.02,
+        max_events=64,
+    ):
+        self.keypad = keypad.ShiftRegisterKeys(
+            clock=clock,
+            data=data,
+            latch=latch,
+            value_to_latch=value_to_latch,
+            key_count=key_count,
+            value_when_pressed=value_when_pressed,
+            interval=interval,
+            max_events=max_events,
+        )
+        super().__init__()