Bump azure-identity in /app-auth/graphapponlytutorial

Bumps [azure-identity](https://github.com/Azure/azure-sdk-for-python) from 1.20.0 to 1.21.0.
- [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_1.20.0...azure-identity_1.21.0)

---
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]

app-auth/graphapponlytutorial/requirements.txt

@@ -20,7 +20,7 @@ azure-core==1.31.0
     # via
     #   azure-identity
     #   microsoft-kiota-authentication-azure
-azure-identity==1.20.0
+azure-identity==1.21.0
     # via
     #   -r requirements.in
     #   msgraph-sdk