chore: remove windows from actions

Ref: #809 (comment)

Author: kentcdodds

.github/workflows/validate.yml

@@ -4,9 +4,8 @@ jobs:
   main:
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest]
         node: [10.14.2, 12, 14, 15]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: ⬇️ Checkout repo
         uses: actions/checkout@v2