fix: correct the format of the OpenAPI examples

[guacs]

Pull Request Checklist

• New code has 100% test coverage
• (If applicable) The prose documentation has been updated to reflect the changes introduced by this PR
• (If applicable) The reference documentation has been updated to reflect the changes introduced by this PR
• Pre-Commit Checks were ran and passed
• Tests were ran and passed

Description

• This PR fixes the format in which the examples are generated.

Close Issue(s)

• Fixes Bug: Incorrectly serialized examples in OpenAPI schema #2272.

[guacs]

The OpenAPI schema requires examples to be in one of the following formats:

• a list of the example values (this should be the values directly and must not include the metadata of an example)
• a dictionary of the examples where the keys are the example name and the values are the example with the other metadata like the description, summary etc.

Reference: https://spec.openapis.org/oas/latest.html#requestBodyObject

[guacs]

For the following model:

@dataclass
class Foo:
    foo: int

Before:

After:

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/2660