chore(diff): fomatter unit test fails locally (#31396)

### Issue # (if applicable)

N/A

### Reason for this change

`format value can handle partial json strings` fails the repo build on my machine. This doesn't happen at the package level, for some reason.

### Description of changes

Made it pass the repo build. 

### Description of how you validated changes

N/A

### 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)

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

Author: comcalvi

packages/@aws-cdk/cloudformation-diff/test/format.test.ts

@@ -5,5 +5,5 @@ const formatter = new Formatter(process.stdout, {});
 
 test('format value can handle partial json strings', () => {
   const output = formatter.formatValue({ nice: 'great', partialJson: '{"wow": "great' }, chalk.red);
-  expect(output).toEqual('{\"nice\":\"great\",\"partialJson\":\"{\\\"wow\\\": \\\"great\"}');
-});
+  expect(output).toEqual(chalk.red('{\"nice\":\"great\",\"partialJson\":\"{\\\"wow\\\": \\\"great\"}'));
+});