Bump msal from 1.26.0 to 1.28.0 (#812)

Bumps [msal](https://github.com/AzureAD/microsoft-authentication-library-for-python) from 1.26.0 to 1.28.0.
- [Release notes](https://github.com/AzureAD/microsoft-authentication-library-for-python/releases)
- [Commits](AzureAD/microsoft-authentication-library-for-python@1.26.0...1.28.0)

---
updated-dependencies:
- dependency-name: msal
  dependency-type: indirect
...

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Author: dependabot[bot]