build(deps-dev): bump starlette from 0.39.1 to 0.39.2 (#551)

Bumps [starlette](https://github.com/encode/starlette) from 0.39.1 to 0.39.2.
- [Release notes](https://github.com/encode/starlette/releases)
- [Changelog](https://github.com/encode/starlette/blob/master/docs/release-notes.md)
- [Commits](encode/starlette@0.39.1...0.39.2)

---
updated-dependencies:
- dependency-name: starlette
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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