Github Release and tag is not created when merging the release PR using the Github CLI

#### Describe the error
Neither a tag, nor a release, is being created when merging the release PR using the Github CLI.

#### Steps to reproduce

1. Push a commit so that a release PR is generated
2. Merge the PR manually so that a release and tag are created
3. Push a commit so that a new release PR is generated
4. Use the Github CLI to merge the release PR, e.g. `gh pr merge --squash`
5. The release PR is merged, but neither a release, nor a tag, is a created

Please refer to the [sample code](https://github.com/nils1k/release-please) that reproduces the issue.

Start with the linked sample repository and reproduce the workflow using the listed steps, especially `gh pr merge --squash`. Compare the manual merge with the GitHub CLI merge; done means both paths create the expected release and tag.

Written by the indexing model from the issue text.