Fix python sample code (tst_scene_render) #24116
Fix bug of python sample code (samples/python/tst_scene_render.py) when backGr or fgr is None (#24114)
1) pass shape tuple to np.zeros arguments instead of integers
2) change np.int to int
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [o] I agree to contribute to the project under Apache 2 License.
- [o] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [o] The PR is proposed to the proper branch
- [o] There is a reference to the original bug report and related work
- [o] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [o] The feature is well documented and sample code can be built with the project CMake
