[serve] Unskip tests in `test_fastapi.py` (#21422)
[serve] Unskip tests in `test_fastapi.py` (#21422)

These tests pass on my machine. Unskipping them here for CI verification.
ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray