Bump azure-core in /packages/autorest.python/test/vanilla/legacy

Bumps [azure-core](https://github.com/Azure/azure-sdk-for-python) from 1.37.0 to 1.38.0.
- [Release notes](https://github.com/Azure/azure-sdk-for-python/releases)
- [Commits](Azure/azure-sdk-for-python@azure-core_1.37.0...azure-core_1.38.0)

---
updated-dependencies:
- dependency-name: azure-core
  dependency-version: 1.38.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

packages/autorest.python/test/vanilla/legacy/requirements.txt

@@ -6,7 +6,7 @@ pytest-asyncio==0.14.0;python_full_version>="3.5.2"
 async_generator;python_full_version>="3.5.2"
 isodate==0.6.1
 msrest==0.7.1
-azure-core==1.37.0
+azure-core==1.38.0
 -e ./Expected/AcceptanceTests/AdditionalProperties
 -e ./Expected/AcceptanceTests/Anything
 -e ./Expected/AcceptanceTests/BodyArray