Drop unused test matrix setup

Author: pimterry

.github/workflows/ci.yml

@@ -5,16 +5,13 @@ jobs:
     name: Build & test
     runs-on: ubuntu-latest
 
-    strategy:
-      matrix:
-        node-version: ["24.x"]
 
     steps:
       - uses: actions/checkout@v4
 
       - uses: actions/setup-node@v4
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: 24.x
 
       - run: npm install --no-package-lock
       - name: Install Playwright for testing