fix: browser_azure_credentials incorrectly decodes saml assertion

[yagohdezg]

Description

When we call the str(base64.urlsafe_b64decode(saml_assertion)) we don't decode the bytes of the encoded assertion, we simply produce a representation of said bytes (you can test this by writing str(b"hello") in a python console and you'll see that the output is "b'hello'", which is not the correct output).

Motivation and Context

The current implementation of BrowserAzureCredentials incorrectly decodes the saml assertion. I changed it to use the more appropiate .decode of python bytes, that correctly decodes utf-8 characters.

Testing

I simply changed saml response base64 and the test token and included problematic characters (such as ") to avoid future problems

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Local run of ./build.sh succeeds
• Code changes have been run against the repository's pre-commit hooks
• Commit messages follow Conventional Commit Specification
• I have read the README document
• I have added tests to cover my changes
• I have run all unit tests using pytest test/unit and they are passing.

License

• By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.