Update SharpYaml dependency to v3.x

Is your feature request related to a problem? Please describe.

OpenAPI.NET currently depends on SharpYaml v2. In my project, I use OpenAPI.NET to process OpenAPI documents and also need to read additional YAML-based configuration files.

SharpYaml v3 is a major redesign that introduces breaking changes compared to v2. Since OpenAPI.NET brings SharpYaml v2 as a dependency, I am currently forced to continue developing against the older SharpYaml API and plan a future migration.

Describe the solution you'd like

I would like OpenAPI.NET to update its SharpYaml dependency from v2 to the latest v3 release.

Describe alternatives you've considered

• Continuing to use SharpYaml v2 in my own code and migrating later.
• Isolating YAML processing behind an abstraction layer to minimize the impact of a future migration.
• Using a different YAML library for application-specific configuration files.

While these approaches are possible, they add complexity that could be avoided if OpenAPI.NET adopted SharpYaml v3 directly.

Locate the project dependency declaration for SharpYaml v2 and review the SharpYaml v3 breaking changes before assessing affected OpenAPI YAML processing. Run the existing test suite after the dependency update; done means SharpYaml v3 is used and OpenAPI document YAML handling remains compatible.