remove matrix.os from gh actions

.github/workflows/main.yml

@@ -4,11 +4,8 @@ on: [push, pull_request]
 
 jobs:
   lint:
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: [windows-latest, ubuntu-latest, macos-latest]
-    name: Test on ${{ matrix.os }}
+    runs-on: ubuntu-latest
+    name: Lint
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -16,7 +13,6 @@ jobs:
           node-version: "14"
       - run: /usr/bin/Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 & echo "Started xvfb"
         shell: bash
-        if: ${{ success() && matrix.os == 'ubuntu-latest' }}
       - run: npm install
       - name: Cache node modules
         uses: actions/cache@v2