ci: add node v18 to test workflow (#150)

Author: amareshsm

.github/workflows/nodejs.yml

@@ -52,7 +52,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        node-version: [12.x, 14.x, 16.x]
+        node-version: [12.x, 14.x, 16.x, 18.x]
         eslint-version: [7.x, 8.x]
         webpack-version: [latest]