💚 add Node.js 15 to tests

Author: blakek

.github/workflows/nodejs.yml

@@ -8,7 +8,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x]
+        node-version: [12.x, 14.x, 15.x]
 
     steps:
       - uses: actions/checkout@v2