Bump stackprof from 0.2.15 to 0.2.20

Bumps [stackprof](https://github.com/tmm1/stackprof) from 0.2.15 to 0.2.20.
- [Release notes](https://github.com/tmm1/stackprof/releases)
- [Changelog](https://github.com/tmm1/stackprof/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tmm1/stackprof/compare/v0.2.15...v0.2.20

)

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

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