fix: disable major node engines updates

lib/manager/npm/extract/index.js

@@ -128,6 +128,7 @@ async function extractDependencies(content, packageFile, config) {
           if (depName === 'node') {
             // This is a special case for Node.js to group it together with other managers
             dep.commitMessageTopic = 'Node.js';
+            dep.major = { enabled: false };
           }
           deps.push(dep);
         }

test/manager/npm/extract/__snapshots__/index.spec.js.snap

@@ -39,6 +39,9 @@ Object {
       "currentVersion": ">= 8.9.2",
       "depName": "node",
       "depType": "engines",
+      "major": Object {
+        "enabled": false,
+      },
       "purl": "pkg:github/nodejs/node",
     },
     Object {