Add LFX Health Score badge (#4749)

Signed-off-by: Maksim Nabokikh <maksim.nabokikh@flant.com>

Author: nabokihms

README.md

@@ -4,7 +4,7 @@
 [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/dexidp/dex/badge?style=flat-square)](https://api.securityscorecards.dev/projects/github.com/dexidp/dex)
 [![OpenSSF Best Practices](https://www.bestpractices.dev/projects/12566/badge)](https://www.bestpractices.dev/projects/12566)
 [![Go Report Card](https://goreportcard.com/badge/github.com/dexidp/dex?style=flat-square)](https://goreportcard.com/report/github.com/dexidp/dex)
-[![Maintainers](https://img.shields.io/badge/Maintainers-CNCF-green?style=flat-square)](MAINTAINERS.md)
+[![LFX Health Score](https://insights.linuxfoundation.org/api/badge/health-score?project=dex)](https://insights.linuxfoundation.org/project/dex/contributors)
 
 ![logo](docs/logos/dex-horizontal-color.png)