build: create release PR as draft and change release PR title

Title will be in the form "chore: release v${version}"

Author: jcouball

release-please-config.json

@@ -8,9 +8,10 @@
       "version-file": "lib/ruby_git/version.rb",
       "bump-minor-pre-major": true,
       "bump-patch-for-minor-pre-major": true,
-      "draft": false,
+      "draft": true,
       "prerelease": false,
-      "include-component-in-tag": false
+      "include-component-in-tag": false,
+      "pull-request-title-pattern": "chore: release v${version}"
     }
   },
   "plugins": [