Get CI node version from file (#1123)

Author: fhammerschmidt

.github/workflows/pull-request.yml

@@ -7,7 +7,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version-file: ".node-version"
           cache: npm
       - run: npm ci
       - run: npx rescript