Update build.yml, do not run with node versions '12', '14',

.github/workflows/build.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [ '12', '14', '16', '20' ]
+        node: [ '16', '20' ]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2