Fix error when installing in envs that don't already have dependencies

[prescod]

Fix #2

[MarcinKonowalczyk]

run into the same thing. bump 👍

[alexc-motif]

@tridao can we merge this? cannot install on certain images otherwise

[tridao]

I've experimented w pyproject.toml before and it works for some cases but for other setups it downloads and installs a different version of pytorch, making installation very slow.
Packaging with torch and CUDA is a headache.
I use pip install causal-conv1d --no-build-isolation.

[alexc-motif]

k, thanks for the context