Group ruby updates for renovate

renovate.json

 {
-  "extends": ["config:recommended", "group:rubyOnRails"]
+  "extends": [
+    "config:recommended",
+    "group:rubyOnRails"
+  ],
+  "packageRules": [
+    {
+      "managers": [
+        "asdf",
+        "bundler",
+        "dockerfile",
+        "devcontainer"
+      ],
+      "matchPackageNames": [
+        "ruby",
+        "mcr.microsoft.com/devcontainers/ruby",
+        "registry.docker.com/library/ruby"
+      ],
+      "groupName": "ruby-updates"
+    }
+  ]
 }