Update anyio requirement from <4.0.0,>=3.7.1 to >=3.7.1,<5.0.0

Updates the requirements on [anyio](https://github.com/agronholm/anyio) to permit the latest version.
- [Release notes](https://github.com/agronholm/anyio/releases)
- [Changelog](https://github.com/agronholm/anyio/blob/master/docs/versionhistory.rst)
- [Commits](agronholm/anyio@3.7.1...4.2.0)

---
updated-dependencies:
- dependency-name: anyio
  dependency-type: direct:production
...

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

requirements-client.txt

@@ -1,4 +1,4 @@
-anyio >= 3.7.1, < 4.0.0
+anyio >= 3.7.1, < 5.0.0
 asgi-lifespan >= 1.0, < 3.0
 cachetools >= 5.3, < 6.0
 cloudpickle >= 2.0, < 4.0