chore(discord-notification): update checkout action to v4

Author: thomasbnt

.github/workflows/discord-notification.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run Discord Webhook
         uses: mrrobotdotapp/classic-discord-webhook@main
         with: