keypad binary sensors should be initially off (#7808)

Co-authored-by: Samuel Sieb <samuel@sieb.net>

esphome/components/binary_sensor/binary_sensor.h

@@ -58,7 +58,7 @@ class BinarySensor : public EntityBase, public EntityBase_DeviceClass {
   void publish_initial_state(bool state);
 
   /// The current reported state of the binary sensor.
-  bool state;
+  bool state{false};
 
   void add_filter(Filter *filter);
   void add_filters(const std::vector<Filter *> &filters);