Bump starlette from 0.38.2 to 0.40.0 in /grai-server/app (#989)

Bumps [starlette](https://github.com/encode/starlette) from 0.38.2 to 0.40.0.
- [Release notes](https://github.com/encode/starlette/releases)
- [Changelog](https://github.com/encode/starlette/blob/master/docs/release-notes.md)
- [Commits](encode/starlette@0.38.2...0.40.0)

---
updated-dependencies:
- dependency-name: starlette
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Ian Eaves <[email protected]>