Add Node.js 26 to Actions test matrix

Author: okuryu

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [20, 22, 24]
+        node-version: [20, 22, 24, 26]
     steps:
       - name: Checkout
         uses: actions/checkout@v6