Exclude parent pom 5.x from renovate updates (#763)

Author: MarkEWaite

.github/renovate.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
-    "config:base",
+    "config:recommended",
     ":semanticCommitsDisabled",
     "schedule:earlyMondays"
   ],
@@ -12,5 +12,13 @@
   "labels": [
     "dependencies"
   ],
+  "packageRules": [
+    {
+      "matchDepNames": [
+        "org.jenkins-ci.plugins:plugin"
+      ],
+      "allowedVersions": "< 5"
+    }
+  ],
   "rebaseWhen": "conflicted"
 }