I am not aware of such a tool. Such a tool however would just be able to check the intended incompatibilities and not bugs, right? So I do not see an alternative to testing.
One thing you may be not aware of is that if you have a professional license, you can install multiple releases in parallel on your machine, so that you can verify MATLAB code yourself.
There are good practices how to create MATLAB code that increases the odds that the code is release independent. On the other hand, this often means to know what relatively new features are - and avoid them for a while.
Last not least, for MATLAB code, there is a high chance that upgrading is a smooth expericence for your customers. And also they can install more releases in parallel. And Technical Support can greatly assist with issues on upgrading.