dropped old node releases, added node 16 (#115)

Author: mcollina

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [6.x, 8.x, 10.x, 12.x, 14.x]
+        node-version: [12.x, 14.x, 16.x]
 
     steps:
       - uses: actions/checkout@v1