Provide a manual mock of the keypad module

This resolves a doc building problem where the `key_count` property
of the Keys object needed to be used.

Author: jepler

docs/conf.py

@@ -8,6 +8,7 @@
 import sys
 
 sys.path.insert(0, os.path.abspath(".."))
+sys.path.insert(0, os.path.abspath("mocks"))
 
 # -- General configuration ------------------------------------------------
 
@@ -45,7 +46,6 @@
     "audiopwmio",
     "audiobusio",
     "audiomp3",
-    "keypad",
 ]
 
 # Add any paths that contain templates here, relative to this directory.

docs/mocks/keypad.py

@@ -0,0 +1,15 @@
+# SPDX-FileCopyrightText: 2021 Jeff Eplerfor Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+class EventQueue:
+    def __init__(self):
+        self.overflowed = False
+
+    def get(self):
+        return None
+
+
+class Keys:
+    def __init__(self, pins, value_when_pressed, pull):
+        self.key_count = len(pins)
+        self.events = EventQueue()