Invalid webhook request payload

### Environment SaaS (https://sentry.io/) ### Steps to Reproduce Since the 27th of February, webhook payloads sent to the endpoint set in an internal integration are not correctly formated. The issue seems to be due to characters not being escaped. So far the I was unable to reproduce. Due to possible PII involved, I'm adding the information to the shadow Jira ticket. ### Expected Result All characters are correctly escaped and the payload is correctly formatted for 3rd party to process. ### Actual Result Incorrect format causes issues during webhook payload processing. ### Product Area Settings - Developer Settings ### Link _No response_ ### DSN _No response_ ### Version _No response_ ┆Issue is synchronized with this [Jira Improvement](https://getsentry.atlassian.net/browse/FEEDBACK-2141) by [Unito](https://www.unito.io)