fix: upgrade GitHub Actions to Node.js 24-compatible versions

Bump actions/checkout v4→v5 and actions/setup-go v5→v6 to resolve
Node.js 20 deprecation warnings.

.github/workflows/sync-champions.yml

@@ -10,10 +10,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout loldle-data
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Checkout loldle
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           repository: tiennm99/loldle
           token: ${{ secrets.LOLDLE_PAT }}

.github/workflows/update-champions.yml

@@ -14,10 +14,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod