Upgrade: Bump httpcore from 0.14.7 to 0.15.0

Bumps [httpcore](https://github.com/encode/httpcore) from 0.14.7 to 0.15.0.
- [Release notes](https://github.com/encode/httpcore/releases)
- [Changelog](https://github.com/encode/httpcore/blob/master/CHANGELOG.md)
- [Commits](encode/httpcore@0.14.7...0.15.0)

---
updated-dependencies:
- dependency-name: httpcore
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -11,7 +11,7 @@ frozenlist==1.3.0
 gitdb==4.0.9
 GitPython==3.1.27
 h11==0.12.0
-httpcore==0.14.7
+httpcore==0.15.0
 httpx==0.22.0
 idna==3.3
 multidict==6.0.2