Fix Leap Years

[trevorb1]

Checklist

• [X] I am running on an up-to-date pypsa-usa environment. Update via conda env update -f envs/environment.yaml

Issue exisits on what branch

Develop

The Issue

If you use a planning horizon with a leap year (ie. 2040), the workflow breaks. I thought I sorted this out in PR #336; but I guess I messed it up. 😅

Steps To Reproduce

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Expected Behavior

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Error Message

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Anything else?

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