remove `test_fastpair_pre_v010.py` when ready

We'll remove [`test_fastpair_pre_v010.py`](https://github.com/carsonfarmer/fastpair/blob/main/fastpair/tests/test_fastpair_pre_v010.py) when ready. Either after next:
1. minor release -- `v0.2.0`; or
2. major release -- `v1.0.0`

Any preference @carsonfarmer?

cc @gegen07