tag_handling_version missing in TranslateTextOptions #80

Since Q4 2025 the new v2 version of the tag handling
has been released, changing some behaviours like for
example enforcing strict xml parsing and others.

Which version to use per default is handled based on
the fact if a key (user) has been using it before 1st
December 2025 (2025-12-01) or since then, which makes
this really hard.

[1] Customers who had not used tag handling prior to
2025-12-01 default to v2. All other customers default
to v1.

Therefore, TranslateTextOptions should get the
constant for the taghandling version or at least
allow it as option (hardcoded) !!

[1] https://developers.deepl.com/docs/xml-and-html-handling/tag-handling-v2#html