CI: Fix wheel builder uploading
The uploading has been broken on nightly wheels for a while.

Hopefully, this fixes it. I've tested on my fork with a dummy token.
> I'm not aware of the anaconda channel adding any value, but I've seen it causing issues when mixed with conda-forge.

In this case, anaconda publishes the anaconda-client to the anaconda channel. The conda-forge version of the client is several versions out of date unfortunately :( .

I'm going to merge this now to test that this works. Ah, ok, makes sense then. It works! https://github.com/pandas-dev/pandas/actions/runs/3404407427