fix cabal plan style: inplace

[csasarak]

Overview

#1256

Checklist

• [ ] I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• [ ] If this PR introduced a user-visible change, I added documentation into docs/.
• [ ] If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an # Unreleased section at the top.
• [ ] If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).