ci: bump actions/checkout and actions/setup-node to v6

Silences the "Node.js 20 actions are deprecated" warning in CI/release
runs. Both actions' v4 tags use a Node 20 runtime that GitHub is
removing from runners on 2026-09-16 (forced Node 24 default from
2026-06-02), so v6 (which ships with the Node 24 runtime) is the
forward-compatible pin.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: kirang89

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '22'
           cache: 'npm'

.github/workflows/release.yml

@@ -16,10 +16,10 @@ jobs:
       id-token: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '22'
           cache: 'npm'