Implement Deepl API's Improve text

[brunobaudry]

With this library, one should be able to use

https://developers.deepl.com/docs/api-reference/improve-text

Cheers

[JanEbbing]

Hi, this is implemented already in DeepLClient. Make sure to use the newest version of the library and replace all uses of Translator with DeepLClient (it's a drop-in replacement).

In code: https://github.com/DeepLcom/deepl-php/blob/main/src/DeepLClient.php#L29

[brunobaudry]

Oh nice !