ci: deprecate AppVoyer integration (#128)

With the migration to GitHub Action, there's no need to continue to use
AppVoyer to only test on Windows, as it's covered by corresponding new
jobs.

Signed-off-by: Khosrow Moossavi <khos2ow@gmail.com>

.github/workflows/test.yml

@@ -13,8 +13,6 @@ on:
 jobs:
   unit:
     runs-on: ubuntu-20.04
-    strategy:
-      fail-fast: true
     steps:
       - name: Checkout
         uses: actions/checkout@v2