test: Add Node.js 18.x to test matrix (#1138)

Author: eps1lon

.github/workflows/validate.yml

@@ -20,7 +20,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
         react: [latest, next, experimental]
     runs-on: ubuntu-latest
     steps: