Fix AppVeyor to only Build on Dev Branch

[X-Guardian]

Pull Request (PR) description

This PR fixes AppVeyor to only build on pushes to the dev branch.

This Pull Request (PR) fixes the following issues

None

Task list

• [ ] Added an entry under the Unreleased section in the CHANGELOG.md. Entry should say what was changed, and how that affects users (if applicable).
• [ ] Resource documentation added/updated in resource directory README.md.
• [ ] Resource parameter descriptions added/updated in schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [ ] Unit tests added/updated. See DSC Resource Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Resource Testing Guidelines.
• [ ] New/changed code adheres to DSC Resource Style Guidelines and Best Practices.

[codecov[bot]]

Codecov Report

Merging #10 into dev will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev      #10   +/-   ##
=======================================
  Coverage   98.93%   98.93%           
=======================================
  Files          16       16           
  Lines        1502     1502           
=======================================
  Hits         1486     1486           
  Misses         16       16

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