[BUG] [csharp] UserAgent not updated in CallApiAsync

Created by: jamesrusso

In ApiClient.cs, The UserAgent is not updated in the CallApiAync method, but it in the CallApi method.

      public Object CallApi(
            String path, RestSharp.Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
            Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
            Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
            String contentType)
        {
            var request = PrepareRequest(
                path, method, queryParams, postBody, headerParams, formParams, fileParams,
                pathParams, contentType);

            // set timeout
            
            RestClient.Timeout = Configuration.Timeout;
            // set user agent
           RestClient.UserAgent = Configuration.UserAgent;

            InterceptRequest(request);
            var response = RestClient.Execute(request);
            InterceptResponse(request, response);

            return (Object) response;
        }

vs

        public async System.Threading.Tasks.Task<Object> CallApiAsync(
            String path, RestSharp.Method method, List<KeyValuePair<String, String>> queryParams, Object postBody,
            Dictionary<String, String> headerParams, Dictionary<String, String> formParams,
            Dictionary<String, FileParameter> fileParams, Dictionary<String, String> pathParams,
            String contentType)
        {
            var request = PrepareRequest(
                path, method, queryParams, postBody, headerParams, formParams, fileParams,
                pathParams, contentType);
            InterceptRequest(request);
            var response = await RestClient.ExecuteTaskAsync(request);
            InterceptResponse(request, response);
            return (Object)response;
        }

I can submit the pull request to fix this template, but wanted some discussion if this should be fixed/set on each request or globally when the RestClient is created. I haven't dug into it this much.