appveyor builds failing due to solarposition with numba warnings

[wholmgren]

#698 introduced a few new checks for warnings with the numba solar position method. These checks seem to fail at random on the appveyor tests.

Options:

• fix/change the test
• add an xfail decorator to the test when on windows

Ideally, someone that uses Windows could reproduce and fix on their machine. @mikofski can you reproduce?

[mikofski]

Sorry for delay ...

[wholmgren]

@mikofski no problem. The new windows tests on azure pipelines in #715 don't error, so I give up.