IncrementalEncoder: Re-add missing update of quarter_count

This lost line caused incremental encoders to stay stuck at 0 forever.

I seem to have lost it while trying to create tidy commits :frown:

shared-module/rotaryio/IncrementalEncoder.c

@@ -65,6 +65,8 @@ void shared_module_softencoder_state_update(rotaryio_incrementalencoder_obj_t *s
         return;
     }
 
+    self->quarter_count += quarter_incr;
+
     if (self->quarter_count >= 4) {
         self->position += 1;
         self->quarter_count = 0;