refactor(app): replace struct device * with const struct device *

Replaced with RegExp: /(?<!const )(struct device \*)/g

See: https://docs.zephyrproject.org/latest/releases/release-notes-2.4.html
PR: #467

app/include/zmk/events/sensor-event.h

@@ -13,7 +13,7 @@
 struct sensor_event {
     struct zmk_event_header header;
     uint8_t sensor_number;
-    struct device *sensor;
+    const struct device *sensor;
     int64_t timestamp;
 };