Bump httpcore from 0.17.2 to 0.17.3

Bumps [httpcore](https://github.com/encode/httpcore) from 0.17.2 to 0.17.3.
- [Release notes](https://github.com/encode/httpcore/releases)
- [Changelog](https://github.com/encode/httpcore/blob/master/CHANGELOG.md)
- [Commits](encode/httpcore@0.17.2...0.17.3)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements-dev.txt

@@ -136,7 +136,7 @@ h2==4.1.0
 
 hpack==4.0.0 ; python_full_version >= '3.6.1'
 
-httpcore==0.17.2 ; python_version >= '3.7'
+httpcore==0.17.3 ; python_version >= '3.7'
 
 httpx[http2]==0.24.1