Group renovate updates for gradle shadow plugin

Author: laurit

.github/renovate.json5

@@ -69,6 +69,10 @@
       "matchPackagePrefixes": ["com.fasterxml.jackson"],
       "groupName": "jackson packages"
     },
+    {
+      "matchPackagePrefixes": ["com.gradleup.shadow"],
+      "groupName": "gradle shadow packages"
+    },
     {
       // prevent update to 2.4-groovy-4.0-SNAPSHOT
       "matchPackageNames": ["org.spockframework:spock-bom"],