Bump approvaltests from 15.3.2 to 16.1.0 in /flowmachine

Bumps [approvaltests](https://github.com/approvals/ApprovalTests.Python) from 15.3.2 to 16.1.0.
- [Release notes](https://github.com/approvals/ApprovalTests.Python/releases)
- [Commits](approvals/ApprovalTests.Python@v15.3.2...v16.1.0)

---
updated-dependencies:
- dependency-name: approvaltests
  dependency-version: 16.1.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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Author: dependabot[bot]