Remove yet another appveyor reference - #8854

PR Summary

Reformatted a check to see if the environment was appveyor

PR Context

Appveyor removed and #8686
I have made it my personal mission to hunt down all these references and destroy them, one by one (or in large quantities as will be seen in my next PR!)

PR Checklist

• PR has a meaningful title
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• Summarized changes
• Change is not breaking
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
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• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed: [docs] [code] AppVeyor/Travis CI references exist #8686
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  • N/A or can only be tested interactively
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