Add deprecated field to SecurityScheme for OpenAPI 3.2.0

[Copilot]

Summary

Successfully implemented the deprecated field for OpenAPI SecurityScheme as specified in OpenAPI 3.2.0 specification.

Changes Made

✅ Core Implementation

• Added Deprecated property to IOpenApiSecurityScheme interface
• Added Deprecated property to OpenApiSecurityScheme class
• Added Deprecated property to OpenApiSecuritySchemeReference class
• Updated OpenApiSecurityScheme copy constructor to include Deprecated

✅ Serialization

• V3.2: Serializes as native deprecated: true field
• V3.1: Serializes as x-oai-deprecated: true extension
• V3.0: Serializes as x-oai-deprecated: true extension
• V2.0: Field is omitted (not supported)

✅ Deserialization

• V3.2: Reads native deprecated field
• V3.1: Reads x-oai-deprecated extension AND deprecated field (forward compatibility)
• V3.0: Reads x-oai-deprecated extension

✅ Testing

• Added 3 serialization tests (V3.2, V3.1, V3.0)
• Added 3 deserialization tests (V3.2, V3.1 with x-oai-deprecated, V3.1 with deprecated)
• All 1,281 tests pass
• Updated test assertions to use JsonNode.DeepEquals for better comparison

✅ Public API

• Updated PublicAPI.approved.txt with new members

✅ Performance

• Updated benchmark results

Verified Behavior

The implementation correctly handles:

1. V3.2: Uses native deprecated field per spec
2. V3.1/V3.0: Uses x-oai- prefix extension for backward compatibility
3. V2.0: Omits deprecated field (not supported in V2)
4. Default value: Field is omitted when false (only serialized when true)
5. Forward compatibility: V3.1 deserializer accepts both extension and native field

Original prompt

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This section details on the original issue you should resolve

<issue_title>SecurityScheme - new deprecated field</issue_title>
<issue_description>OAI 3.2.0 defines a new deprecated field (bool)

We should add the new field to the model, and implement serialization/deserialization.

For OpenAPi 3.1.0 serialization, we should use a x-oai- prefix to make it an extension</issue_description>

<agent_instructions>Make sure to update the public api export file.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #15

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[baywet]

@copilot run the following commands cd performance/benchmark && dotnet run -c Release -- EmptyModels and commit the results, do nothing else

[Copilot]

@copilot run the following commands cd performance/benchmark && dotnet run -c Release -- EmptyModels and commit the results, do nothing else

Ran the benchmark command and committed the updated results in 2e42719.