Add support for output_format, code included

[machj]

Describe the bug
The new version of the API https://www.deepl.com/cs/docs-api/documents/translate-document includes support for the optional output_format parameter, but there is no implementation in deepl-dotnet.

To Reproduce
var options = new DocumentTranslateOptions();
options.OutputFormat = "docx";

Expected behavior
DocumentTranslateOptions have an OutputFormat parameter, I can set it to "docx" to change PDF to Word during translation.

Screenshots or sample code
Expected final code:

var translator = new Translator(ServiceApiKey);
var options = new DocumentTranslateOptions();
options.OutputFormat = "docx";
var handle = await translator.TranslateDocumentUploadAsync(filepath, sourceLanguage, targetLanguage, options);

Files to change:

DeepL/DocumentTranslateOptions.cs

    /// <summary>File extension of desired format of translated file, for example: docx.</summary>
    /// If unspecified, by default the translated file will be in the same format as the input file.
    public string? OutputFormat { get; set; }

DeepL/Translator.cs

/// <inheritdoc />
public async Task<DocumentHandle> TranslateDocumentUploadAsync(
      Stream inputFile,
      string inputFileName,
      string? sourceLanguageCode,
      string targetLanguageCode,
      DocumentTranslateOptions? options = null,
      CancellationToken cancellationToken = default) {
  var bodyParams = CreateCommonHttpParams(
        sourceLanguageCode,
        targetLanguageCode,
        options?.Formality,
        options?.GlossaryId);

  if (options?.OutputFormat != null) {
    bodyParams.Add(("output_format", options.OutputFormat));
  }

  using var responseMessage =  
(...)

[JuergenRB]

@daniel-jones-dev May I ask what the status is and if you have any feedback on the change