[BUG] Check for formalitySupportedLanguages missing

[ZHENYAio]

Describe the bug
German is the default language of my TYPO3 installation, English [EN-GB] is a translation (and some more languages).
In the extension settings I set the formality to "more".
When I want to translate something from German into English, the translation fails (fallback to German content). All other translations are fine.
I analyzed it and found that the API response in DeeplService::translateRequest says that the target language doesn't support the formality parameter.
I removed the formality in the settings and now it's fine.

DeeplService::$formalitySupportedLanguages is set in DeeplService::loadSupportedLanguages(), but never checked?

To Reproduce

• Set formality.
• Translate using Deepl into a language that doesn't support formality (example EN-GB).

Expected behavior
When translating, the $formalitySupportedLanguages should be considered. If the target language doesn't support formality, the formality parameter should be omitted.

TYPO3 Setup

• TYPO3 Version: 11.5.30
• PHP version: 8.1
• Extension version: 3.0.5