Code samples in package READMEs need to be tested as part of the CI/CD process

### Type

Task

### Scope

Multi-theme or Platform

### Skillset

dev ops

### Description

Several of the READMEs in the various Pydantic packages have code examples that will very quickly get out of date. We need to test these as part of the CI/CD process, similar to the way we test queries in Docusaurus.