[REQ] [Swift] Remove unused parameter from function

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

The createURLRequest function receives a headers parameter, but it is not used within the function.

    open func createURLRequest(urlSession: URLSessionProtocol, method: HTTPMethod, encoding: ParameterEncoding, headers: [String: String]) throws -> URLRequest {

        guard let url = URL(string: URLString) else {
            throw DownloadException.requestMissingURL
        }

        var originalRequest = URLRequest(url: url)

        originalRequest.httpMethod = method.rawValue

        buildHeaders().forEach { key, value in
            originalRequest.setValue(value, forHTTPHeaderField: key)
        }

        let modifiedRequest = try encoding.encode(originalRequest, with: parameters)

        return modifiedRequest
    }

Describe the solution you'd like

Remove unused 'headers' parameter from createURLRequest function
The headers parameter is not needed as the buildHeaders() function handles the headers internally

    open func createURLRequest(urlSession: URLSessionProtocol, method: HTTPMethod, encoding: ParameterEncoding) throws -> URLRequest {

        guard let url = URL(string: URLString) else {
            throw DownloadException.requestMissingURL
        }

        var originalRequest = URLRequest(url: url)

        originalRequest.httpMethod = method.rawValue

        buildHeaders().forEach { key, value in
            originalRequest.setValue(value, forHTTPHeaderField: key)
        }

        let modifiedRequest = try encoding.encode(originalRequest, with: parameters)

        return modifiedRequest
    }

Search the Swift generator templates and call sites for createURLRequest, then inspect how buildHeaders supplies request headers. Remove the unused parameter from the function and update its callers; done means the generated Swift client still builds and its existing tests pass.