build: bump azure-identity from 1.18.0 to 1.19.0

Bumps [azure-identity](https://github.com/Azure/azure-sdk-for-python) from 1.18.0 to 1.19.0.
- [Release notes](https://github.com/Azure/azure-sdk-for-python/releases)
- [Changelog](https://github.com/Azure/azure-sdk-for-python/blob/main/doc/esrp_release.md)
- [Commits](Azure/azure-sdk-for-python@azure-identity_1.18.0...azure-identity_1.19.0)

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

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

Author: dependabot[bot]

poetry.lock

@@ -15,7 +15,7 @@ streamlit = "1.39.0"
 python-dotenv = "1.0.1"
 azure-ai-formrecognizer = "3.3.3"
 azure-storage-blob = "12.20.0"
-azure-identity = "1.18.0"
+azure-identity = "1.19.0"
 flask = {extras = ["async"], version = "^3.0.3"}
 openai = "1.48.0"
 langchain = "0.2.16"