Configure dependabot bundler updates (#724)

Author: mokagio

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: bundler
+    directory: "/"
+    schedule:
+      interval: daily
+    groups:
+      ruby-minor-and-patch:
+        update-types: [minor, patch]
+    open-pull-requests-limit: 5

CHANGELOG.md

@@ -19,6 +19,7 @@ _None_
 ### Internal Changes
 
 - `openai_ask`: validate named function tools, default to `gpt-4.1`, use `max_completion_tokens`, and opt out of OpenAI request storage. [#719]
+- Configure Dependabot to update Ruby dependencies daily, grouping minor/patch bumps under `ruby-minor-and-patch`. [#724]
 
 ## 14.6.0