### Apache Airflow version

2.5.1

### What happened

/calendar page give a problem, here is the capture



![屏幕截图 2023-01-30 093116](https://user-images.githubusercontent.com/19165258/215369479-9fc7de5c-f190-460c-9cf7-9ab27d8ac355.png)


### What you think should happen instead

_No response_

### How to reproduce

_No response_

### Operating System

Ubuntu 22.04.1 LTS

### Versions of Apache Airflow Providers

Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:        22.04
Codename:       jammy

### Deployment

Other

### Deployment details


Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:        22.04
Codename:       jammy

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

and form_fields[k]["schema"]["description_html"]
            ):
                form_fields[k]["description"] = Markup(form_fields[k]["schema"]["description_html"])
            if "custom_html_form" in form_fields[k]["schema"]:
                form_fields[k]["schema"]["custom_html_form"] = Markup(
                    form_fields[k]["schema"]["custom_html_form"]
                )
        if not dag_orm:
            flash(f"Cannot find dag {dag_id}")
            return redirect(origin)
        if dag_orm.has_import_errors:
            flash(f"Cannot create dagruns because the dag {dag_id} has import errors", "error")
            return redirect(origin)
        recent_runs = (
            session.query(
                DagRun.conf, func.max(DagRun.run_id).label("run_id"), func.max(DagRun.execution_date)
            )
            .filter(
                DagRun.dag_id == dag_id,
                DagRun.run_type == DagRunType.MANUAL,
                DagRun.conf.isnot(None),
            )
            .group_by(DagRun.conf)
            .order_by(func.max(DagRun.execution_date).desc())
            .limit(5)
            .all()
        )
        recent_confs = {}
        for run in recent_runs:
            recent_conf = getattr(run, "conf")