chore(README): remove Mergify badge (#32963)

### Reason for this change

Badge does not render properly

### Description of changes

Removing this badge that does not render properly, or alternatively follow https://docs.mergify.com/badge/#finding-the-badge-url to restore if still applicable 

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

README.md

@@ -7,7 +7,6 @@
 [![NuGet version](https://badge.fury.io/nu/Amazon.CDK.Lib.svg)](https://badge.fury.io/nu/Amazon.CDK.Lib)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/software.amazon.awscdk/aws-cdk-lib/badge.svg)](https://maven-badges.herokuapp.com/maven-central/software.amazon.awscdk/aws-cdk-lib)
 [![Go Reference](https://pkg.go.dev/badge/github.com/aws/aws-cdk-go/awscdk/v2.svg)](https://pkg.go.dev/github.com/aws/aws-cdk-go/awscdk/v2)
-[![Mergify](https://img.shields.io/endpoint.svg?url=https://gh.mergify.io/badges/aws/aws-cdk&style=flat)](https://mergify.io)
 
 [![View on Construct Hub](https://constructs.dev/badge?package=aws-cdk-lib)](https://constructs.dev/packages/aws-cdk-lib)