ci: don't run ESLint v9 on unsupported versions of Node

Author: G-Rath

.github/workflows/validate.yml

@@ -30,6 +30,18 @@ jobs:
             testing-library-dom: 9
           - node: 12
             testing-library-dom: 9
+          - node: 12.22.0
+            eslint: 9
+          - node: 12
+            eslint: 9
+          - node: 14.17.0
+            eslint: 9
+          - node: 14
+            eslint: 9
+          - node: 16.0.0
+            eslint: 9
+          - node: 16
+            eslint: 9
     runs-on: ubuntu-latest
     steps:
       - name: ⬇️ Checkout repo