Update GitHub Actions to use latest versions

Author: pifopi

.github/workflows/jsoncheck.yml

@@ -12,9 +12,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v6
 
       - name: Check JSON syntax
-        uses: limitusus/json-syntax-check@v1
+        uses: limitusus/json-syntax-check@v2
         with:
           pattern: "\\.json$"