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/widgets/switch/lv_example_switch_1.py

@@ -1,6 +1,6 @@
 def event_handler(e):
     code = e.get_code()
-    obj = lv.switch.__cast__(e.get_target())
+    obj = e.get_target()
     if code == lv.EVENT.VALUE_CHANGED:
         if obj.has_state(lv.STATE.CHECKED):
             print("State: on")