Add option to pull target branch automatically after squash merge

[JustinGrote]

When following this workflow:

1. Create Pull Request
2. Merge Pull Request using squash in vscode
3. Click the "Delete Branches" button

At the end of the series, you end up back at the target branch locally, however the target branch doesn't have the changes yet and you must manually git pull to see the changes.

There should be a setting to automatically pull the target branch after a completed PR to avoid starting new work when the old work isn't "visible" yet

Reproduction