Bump azure-identity in /samples/web-app-managed-identity/python/src (#83)

Bumps [azure-identity](https://github.com/Azure/azure-sdk-for-python) from 1.12.0 to 1.16.1.
- [Release notes](https://github.com/Azure/azure-sdk-for-python/releases)
- [Commits](Azure/azure-sdk-for-python@azure-identity_1.12.0...azure-identity_1.16.1)

---
updated-dependencies:
- dependency-name: azure-identity
  dependency-version: 1.16.1
  dependency-type: direct:production
...

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Author: dependabot[bot]

samples/web-app-managed-identity/python/src/requirements.txt

@@ -1,5 +1,5 @@
 Flask==3.1.0
-azure-identity==1.12.0
+azure-identity==1.16.1
 azure-storage-blob==12.26.0
 azure-core==1.35.0
 gunicorn==23.0.0