Bump pyssim from 0.4 to 0.7

Bumps [pyssim](https://github.com/jterrace/pyssim) from 0.4 to 0.7.
- [Changelog](https://github.com/jterrace/pyssim/blob/master/CHANGES.md)
- [Commits](jterrace/pyssim@v0.4...v0.7)

---
updated-dependencies:
- dependency-name: pyssim
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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