Triggering a dagrun with naive datetime raises an HTML page instead of JSON

**Apache Airflow version**:2.0


**What happened**:

An HTML page was returned instead of json when the REST API was triggered with a naive datetime

**What you expected to happen**:

I expected it to raise error status 400 indicating that it's a bad request

**How to reproduce it**:
1. Start the web server and scheduler inside breeze.
2. Make a post request to this endpoint: http://localhost:28080/api/v1/dags/example_bash_operator/dagRuns
 to trigger dagruns using this request body: {"execution_date": "2020-11-09T16:25:56.939143"}. or any naive datetime
3. See that an HTML is raised instead of Json

airflow/api_connexion/endpoints/dag_run_endpoint.py
limit,
        offset,
    )
    return dagrun_collection_schema.dump(DAGRunCollection(dag_runs=dag_run, total_entries=total_entries))
def _fetch_dag_runs(
    query,
    end_date_gte,
    end_date_lte,
    execution_date_gte,
    execution_date_lte,
    start_date_gte,
    start_date_lte,
    limit,
    offset,
):
    query = _apply_date_filters_to_query(
        query,
        end_date_gte,
        end_date_lte,
        execution_date_gte,
        execution_date_lte,
        start_date_gte,
        start_date_lte,
    )
    
    total_entries = query.count()
    
    dag_run = query.order_by(DagRun.id).offset(offset).limit(limit).all()
    return dag_run, total_entries
def _apply_date_filters_to_query(