chore: add OpenSSF Scorecard badge (#3154)

chore: add OpenSSF scorecard

Signed-off-by: CI <ci@argoproj.com>
Co-authored-by: CI <ci@argoproj.com>

README.md

@@ -4,6 +4,7 @@
 [![codecov](https://codecov.io/gh/argoproj/argo-rollouts/branch/master/graph/badge.svg)](https://codecov.io/gh/argoproj/argo-rollouts)
 [![slack](https://img.shields.io/badge/slack-argoproj-brightgreen.svg?logo=slack)](https://argoproj.github.io/community/join-slack)
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/3834/badge)](https://bestpractices.coreinfrastructure.org/projects/3834)
+[![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/argoproj/argo-rollouts/badge)](https://api.securityscorecards.dev/projects/github.com/argoproj/argo-rollouts)
 [![Artifact HUB](https://img.shields.io/endpoint?url=https://artifacthub.io/badge/repository/argo-rollouts)](https://artifacthub.io/packages/helm/argo/argo-rollouts)
 
 ## What is Argo Rollouts?