Remove deprecated basic_chain method

[AdamRJensen]

• [ ] Closes #xxxx
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I stumbled upon the basic_chain method, which has been deprecated since 0.9.1, hence it seemed time to do a cleanup and remove it entirely.

Perhaps it is preferred to wait until a major release?

[kandersolar]

Perhaps it is preferred to wait until a major release?

Yes, regardless of how long it's been since the deprecation was put in place, I think we should not remove functionality in minor releases.

[kandersolar]

There is a comment mentioning basic_chain on line 44 in modelchain.py that could be edited as well :)

[wholmgren]

Thanks for cleaning up this early experiment @AdamRJensen.

As an aside, here's a link to another, not quite as early experiment using dask and basic chain: wholmgren/pvlib-python mcdask. As we remove this code, just wanting to document that there is unexplored potential using model chain functions instead of the bloated classes.