fix: Updates to take latest serde_valid in rust-server generator

[dsteeley]

Code changes required to take serde_valid. Note these changes are slightly academic as the rust-server has compile time enum verification so this isn't hit.

I don't want to remove this case as there's a risk it's used in a future change. Therefore fixing here.

PR checklist

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  ./mvnw clean package || exit
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Summary by cubic

Update the Rust server generator to work with the latest serde_valid, fixing enum validation and bumping swagger to 7.0.1. This keeps generated projects compiling when the validate feature is enabled.

• Bug Fixes

  • Switch enum validation attribute to validate(r#enum(...)) in validate.mustache to match current serde_valid.

• Dependencies

  • Update swagger from 7.0.0 to 7.0.1 in Cargo.mustache and all sample Cargo.toml files.

^{Written for commit f2653bd. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 9 files

_{Re-trigger cubic}