fix: swagger ui missing openapi.json

[smitt14ua]

Summary

Fix path to openapi.json.
Old path was relative to Swagger UI page, so script tried to fetch /swagger/swagger/openapi.json instead of /swagger/openapi.json

How to test

Go to <your-app>/swagger and check network activities for openapi.json request

[gemini-code-assist]

Code Review

This pull request modifies the OpenAPI UI handler to use an absolute path for the Swagger JSON specification. A review comment suggests avoiding this hardcoded path as it may cause issues when the application is hosted under a subpath, recommending instead to use the specification URL parameter already passed to the handler function.