[BUG][rust-server] Regexes and validation are broken

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The rust-server generator uses the regex, validator and lazy_static crates. Since version 0.17.0 of validator, a breaking change was introduced that changed how to access regexes produced by regex and using lazy_static, as referred here: https://github.com/Keats/validator/issues/311#issuecomment-2013865902.

The generated code should be changed accordingly.

openapi-generator version

7.4.0

OpenAPI declaration file content or url

Unmodified petstore on openapi 3.0, available here: https://github.com/OAI/OpenAPI-Specification/blob/main/examples/v3.0/petstore.yaml

Generation Details

No special parameter or step is necessary.

Steps to reproduce

• Generate a rust-server project using the petstore file.
• Try to compile the generated project, an error will arise.

Related issues/PRs

https://github.com/Keats/validator/issues/311#issuecomment-2013865902

Suggest a fix

Two possible fixes:

• Downgrade and pin validator to 0.16.1 (easy and fast but not ideal)
• Fix the generated code (ideal solution but takes more time)

I will try to get a look at it.

Generate a rust-server project from the linked OpenAPI petstore specification, then compile it to reproduce the validator error. Inspect the generated validation code and its regex, validator, and lazy_static dependency declarations; done means the generated project compiles with validator 0.17.0 or later.