Apache Airflow Git provider: Git provider hook defaults to StrictHostKeyChecking=no, disabling SSH host-key verification

The Apache Airflow Git provider runs its git-over-SSH operations with `StrictHostKeyChecking=no` by default, disabling SSH host-key verification. An attacker who can intercept the network path between an Airflow worker and the Git server can impersonate the server (man-in-the-middle), capturing the SSH deploy key or injecting malicious repository content. Deployments that use the Git DAG bundle or Git provider to clone over SSH with a deploy key are affected. The fix changes the default to verify host keys; upgrade to apache-airflow-providers-git `0.4.1` or later and configure a `known_hosts` file.