Update schema-tests.yaml

Author: ralfhandl

.github/workflows/schema-tests.yaml

@@ -24,7 +24,7 @@ jobs:
 
       - uses: actions/setup-node@v6 # setup Node.js
         with:
-          node-version: "22.x"
+          node-version: "20.x"
 
       - name: Install dependencies
         run: npm ci