Fix AttributeError while using the function update_state

[fuatcakici]

The update_state function in the DagRun class fails as ever since an update was made to Airflow, the state of the DagRun is returned as a string instead of an actual DagRunState. However, should this be fixed in the future, this change would still not affect anything since the state is called as a string here, which would return the value without needing to specify ".value" anyway.

Fixes #34604

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[boring-cyborg]

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[dirrao]

LGTM

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.