fix(parser): honor inferSchemaType for OAS 3.1 enum schemas

[zetacollab]

Pull Request

---

Description

This PR fixes an OpenAPI 3.1 parser inconsistency when ParseOptions.setInferSchemaType(false) is used.

In the OAS 3.1 getJsonSchema(...) path, enum-based type inference was still applied even when schema type inference was explicitly disabled. As a result, schemas like:

contains:
  enum:
    - 1

were parsed with an invented type instead of preserving an unset type.

This PR updates that path to honor inferSchemaType(false) and adds a regression test covering the issue.

Fixes [#1964](https://github.com/swagger-api/swagger-parser/pull/2299)

## Type of Change

- [x] 🐛 Bug fix
- [ ] ✨ New feature
- [ ] ♻️ Refactor (non-breaking change)
- [x] 🧪 Tests
- [ ] 📝 Documentation
- [ ] 🧹 Chore (build or tooling)

## Checklist

- [x] I have added/updated tests as needed
- [ ] I have added/updated documentation where applicable
- [x] The PR title is descriptive
- [x] The code builds and passes tests locally
- [x] I have linked related issues (if any)

## Screenshots / Additional Context

Locally verified with:

mvn -pl modules/swagger-parser-v3 -am -Dsurefire.failIfNoSpecifiedTests=false -Dtest=OAI31DeserializationTest#test31Issue1964InferSchemaTypeDisabled test
mvn -pl modules/swagger-parser-v3 -am -Dsurefire.failIfNoSpecifiedTests=false -Dtest=OAI31DeserializationTest#testSchemaKeysOAS31 test

The regression test confirms that with inferSchemaType(false):

- contains: { enum: [1] } does not get an inferred type
- additionalProperties: false does not force an object type