trackmania-rl/tmrl: Release 0.5.1

Release 0.5.1 This release complies with rtgym>=0.9, which in turns complies with the gymnasium signature of the reset function. In case you are using custom rtgym interfaces in tmrl, you will want to update your reset implementations. This is straightforward, you can just replace: def reset(self): with: def reset(self, seed=None, options=None)