fix(examples) remove cast in MP scripts (#2354)

After https://github.com/lvgl/lv_binding_micropython/pull/161 merged, it is no longer needed to cast the result of 'e.get_target()'

Also, additional small fixes to allow CI improvements

examples/event/lv_example_event_1.py

@@ -17,7 +17,7 @@ class Event_1():
     def event_cb(self,e):
         print("Clicked");
             
-        btn = lv.btn.__cast__(e.get_target())
+        btn = e.get_target()
         label = btn.get_child(0)
         label.set_text(str(self.cnt))
         self.cnt += 1