admin: update CI tests to use supported node version

Author: ricmoo

.github/workflows/nodejs.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [ 12.x, 14.x, 16.x ]
+        node-version: [ 18.x, 20.x ]
 
     steps:
       - name: Use Node.js ${{ matrix.node-version }}
@@ -53,7 +53,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v1
         with:
-          node-version: 12.x
+          node-version: 20.x
 
       - name: Checkout repository
         uses: actions/checkout@v2
@@ -112,7 +112,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v1
         with:
-          node-version: 12.x
+          node-version: 20.x
 
       - name: Checkout repository
         uses: actions/checkout@v2