ci: group ruby-version updates together

renovate-common.json

@@ -103,6 +103,12 @@
         "golang-version"
       ],
       "separateMinorPatch": true
+    },
+    {
+      "matchDatasources": [
+        "ruby-version"
+      ],
+      "groupName": "ruby-version"
     }
   ]
 }