Bump approvaltests from 15.1.0 to 15.1.1 in /flowmachine

Bumps [approvaltests](https://github.com/approvals/ApprovalTests.Python) from 15.1.0 to 15.1.1.
- [Release notes](https://github.com/approvals/ApprovalTests.Python/releases)
- [Commits](approvals/ApprovalTests.Python@v15.1.0...v15.1.1)

---
updated-dependencies:
- dependency-name: approvaltests
  dependency-version: 15.1.1
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]