Only test against ubuntu

Author: mrecachinas

.github/workflows/build_test.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         node-version: [10.x, 12.x, 14.x]
-        platform: [ubuntu-latest, macos-latest, windows-latest]
+        platform: [ubuntu-latest]
 
     steps:
     - uses: actions/checkout@v2