ci (node.js) : change version for node js test

14.x => 12.x

Author: firestar300

.github/workflows/node.js.yml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [14.x]
+        node-version: [12.x]
 
     steps:
     - uses: actions/checkout@v2