Bump starlette from 0.38.5 to 0.40.0

Bumps [starlette](https:/encode/starlette) from 0.38.5 to 0.40.0.
- [Release notes](https:/encode/starlette/releases)
- [Changelog](https:/encode/starlette/blob/master/docs/release-notes.md)
- [Commits](encode/starlette@0.38.5...0.40.0)

---
updated-dependencies:
- dependency-name: starlette
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

dev-requirements.txt

@@ -210,7 +210,7 @@ sphinxcontrib-openapi==0.8.4
 sphinxcontrib-qthelp==2.0.0
 sphinxcontrib-serializinghtml==2.0.0
 stack-data==0.6.3
-starlette==0.38.5
+starlette==0.40.0
 stomp-py==8.1.2
 suitcase-mongo==0.6.0
 suitcase-msgpack==0.3.0