Bump httpx from 0.26.0 to 0.27.0 in /backend

Bumps [httpx](https://github.com/encode/httpx) from 0.26.0 to 0.27.0.
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](encode/httpx@0.26.0...0.27.0)

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

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

Author: dependabot[bot]

backend/requirements-docker.txt

@@ -1,7 +1,7 @@
 ariadne==0.22
 asyncpg==0.29.0
 fastapi==0.109.2
-httpx==0.26.0
+httpx==0.27.0
 pydantic==2.6.1
 python-multipart==0.0.9
 python-jose==3.3.0

backend/src/requirements_docker.txt

@@ -1,6 +1,6 @@
 ariadne==0.21
 fastapi==0.109.2
-httpx==0.26.0
+httpx==0.27.0
 psycopg2-binary==2.9.9
 pydantic==2.5.3
 python-multipart==0.0.7