Main branch renamed to `trunk`

[coder-karen]

On 17 June 2022 the main branch of this repository was renamed to trunk. For anyone developing with Jetpack locally, you can update your repository by running the following commands:

git branch -m master trunk
git fetch origin
git branch -u origin/trunk trunk
git remote set-head origin -a

No change is needed on existing PRs as GitHub will handle this automatically. Thank you!