fix to stop running ci on windows

To temporarily avoid the problem that Graphviz for Windows is experiencing with the 2.44 version. #249

.github/workflows/node-ci.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         node-version: [8.x, 10.x, 12.x]
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest]
 
     steps:
     - uses: actions/checkout@v1