chore: add security scorecard to readme (#166)

Author: Kenneth Rosario

README.md

@@ -1,4 +1,4 @@
-# Functions Framework for Ruby [![Documentation](https://img.shields.io/badge/docs-FunctionsFramework-red.svg)](https://googlecloudplatform.github.io/functions-framework-ruby/latest) [![Gem Version](https://badge.fury.io/rb/functions_framework.svg)](https://badge.fury.io/rb/functions_framework)
+# Functions Framework for Ruby [![Documentation](https://img.shields.io/badge/docs-FunctionsFramework-red.svg)](https://googlecloudplatform.github.io/functions-framework-ruby/latest) [![Gem Version](https://badge.fury.io/rb/functions_framework.svg)](https://badge.fury.io/rb/functions_framework) ![Security Scorecard](https://api.securityscorecards.dev/projects/github.com/GoogleCloudPlatform/functions-framework-ruby/badge)
 
 An open source framework for writing lightweight, portable Ruby functions that
 run in a serverless environment. Functions written to this Framework will run