Make Gemini trigger on PRs automatically (#489)

This makes it easier for the developer to remember to consult Gemini
as part of team-review.

Author: thorkildcognite

.gemini/config.yaml

@@ -5,6 +5,7 @@ code_review:
   max_review_comments: -1
   pull_request_opened:
     help: false
-    summary: false
-    code_review: false
+    summary: true
+    code_review: true
+    include_drafts: true
 ignore_patterns: []