Apache Airflow FAB provider: FAB auth manager: JWT signature verification disabled by default for Azure AD OAuth (`verify_signature` defaults to `False`)

The FAB auth manager's Azure AD OAuth login defaulted verify_signature=False when decoding the ID token, so an attacker able to present a forged or unsigned (alg:none) ID token to the OAuth callback could bypass authentication and log in as an arbitrary user, including one holding the Admin role (CWE-347). Deployments running the FAB auth manager with the Azure AD OAuth login path under its default configuration are affected; the Authentik path already defaulted to True. This issue affects apache-airflow-providers-fab before 3.7.3. Users are advised to upgrade to apache-airflow-providers-fab 3.7.3, which defaults verify_signature=True.