Update opentelemetry-instrumentation-httpx requirement in /code/function

Updates the requirements on [opentelemetry-instrumentation-httpx](https://github.com/open-telemetry/opentelemetry-python-contrib) to permit the latest version.
- [Release notes](https://github.com/open-telemetry/opentelemetry-python-contrib/releases)
- [Changelog](https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/CHANGELOG.md)
- [Commits](https://github.com/open-telemetry/opentelemetry-python-contrib/commits)

---
updated-dependencies:
- dependency-name: opentelemetry-instrumentation-httpx
  dependency-type: direct:production
...

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

Author: dependabot[bot]

code/function/requirements.txt

@@ -9,5 +9,5 @@ pydantic-settings~=2.7.0
 httpx~=0.28.1
 azure-monitor-opentelemetry-exporter==1.0.0b32
 opentelemetry-instrumentation-fastapi==0.49b2
-opentelemetry-instrumentation-httpx~=0.49b2
+opentelemetry-instrumentation-httpx~=0.50b0
 opentelemetry-instrumentation-system-metrics~=0.50b0