Bug report: 'JSON beautify' operation losing numeric precision

### Summary

When running the 'JSON beautify' operation, numeric precision is lost for large numbers.

### Example

https://gchq.github.io/CyberChef/#recipe=JSON_Beautify('%5C%5Ct')&input=eyAiYSI6IDEyMzQ1Njc4OTAxMjM0NTY3ODkgfQ

Input:
```json
{ "a": 1234567890123456789 }
```

Erroneous output:
``` json
{
"a": 1234567890123456800
}
```