Remove Node.js 18 from CI testing matrix

- Test only on Node.js 20.x and 22.x for more focused CI runs
- Node.js 18 support is maintained but not actively tested in CI
- Reduces CI complexity while maintaining coverage of current LTS versions

Author: omar-dulaimi

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x, 20.x, 22.x]
+        node-version: [20.x, 22.x]
 
     steps:
     - name: Checkout code