Can't build with Rust stable toolchain

[eitsupi]

The changes made by #233 prevent builds except for nightly-toolchain.
https://github.com/pola-rs/r-polars/actions/runs/5411224946/jobs/9833719506?pr=274

Can we revert this change for now? Or Could you fix that error?

Originally posted by @eitsupi in #80 (comment)

[sorhawell]

@Sicheng-Pan @eitsupi
Sorry that is a blunder from my side, I overlooked PR used an unstable feature.

I think there is tag to forbid the compiler to use unstable features.

I will make a dumb hotfix for now.

@Sicheng-Pan maybe you can find another way to bubble the various errors.

[Sicheng-Pan]

@sorhawell Yeah I should have avoided using nightly features. I checked your PR and it looks good to me.

[eitsupi]

Thanks for taking a look at this right away!
I think it is definitely necessary to test the build on CI with the stable toolchains. (#274)