Add Linux Foundation Health Score badge to README (apache#56018)

Congrats! We have onboarded Apache Airflow to LFX Insights, the Linux Foundation's platform for monitoring the world's most critical open-source projects.

https://insights.linuxfoundation.org/project/apache-airflow

Author: jonathimer

README.md

@@ -25,7 +25,7 @@
 | License    | [![License](https://img.shields.io/:license-Apache%202-blue.svg)](https://www.apache.org/licenses/LICENSE-2.0.txt)                                                                                                                                                                                                                                                                                                                                               |
 | PyPI       | [![PyPI version](https://badge.fury.io/py/apache-airflow.svg)](https://badge.fury.io/py/apache-airflow) [![PyPI - Python Version](https://img.shields.io/pypi/pyversions/apache-airflow.svg)](https://pypi.org/project/apache-airflow/) [![PyPI - Downloads](https://img.shields.io/pypi/dm/apache-airflow)](https://pypi.org/project/apache-airflow/)                                                                                                           |
 | Containers | [![Docker Pulls](https://img.shields.io/docker/pulls/apache/airflow.svg)](https://hub.docker.com/r/apache/airflow) [![Docker Stars](https://img.shields.io/docker/stars/apache/airflow.svg)](https://hub.docker.com/r/apache/airflow) [![Artifact HUB](https://img.shields.io/endpoint?url=https://artifacthub.io/badge/repository/apache-airflow)](https://artifacthub.io/packages/search?repo=apache-airflow)                                                  |
-| Community  | [![Contributors](https://img.shields.io/github/contributors/apache/airflow)](https://github.com/apache/airflow/graphs/contributors) [![Slack Status](https://img.shields.io/badge/slack-join_chat-white.svg?logo=slack&style=social)](https://s.apache.org/airflow-slack) ![Commit Activity](https://img.shields.io/github/commit-activity/m/apache/airflow) [![OSSRank](https://shields.io/endpoint?url=https://ossrank.com/shield/6)](https://ossrank.com/p/6) |
+| Community  | [![Contributors](https://img.shields.io/github/contributors/apache/airflow)](https://github.com/apache/airflow/graphs/contributors) [![Slack Status](https://img.shields.io/badge/slack-join_chat-white.svg?logo=slack&style=social)](https://s.apache.org/airflow-slack) ![Commit Activity](https://img.shields.io/github/commit-activity/m/apache/airflow) [![OSSRank](https://shields.io/endpoint?url=https://ossrank.com/shield/6)](https://ossrank.com/p/6) [![LFX Health Score](https://insights.linuxfoundation.org/api/badge/health-score?project=apache-airflow)](https://insights.linuxfoundation.org/project/apache-airflow) |