add Accept-Encoding: utf-8 to header

reason for this change is avoiding to get unicode escape characters in response for non-ANSI characters

potential fix for issue #541

bot/plugins/deepl.py

@@ -42,10 +42,11 @@ async def execute(self, function_name, helper, **kwargs) -> Dict:
         headers = {
             "Authorization": f"DeepL-Auth-Key {self.api_key}",
             "User-Agent": "chatgpt-telegram-bot",
-            "Content-Type": "application/x-www-form-urlencoded"
+            "Content-Type": "application/x-www-form-urlencoded",
+            "Accept-Encoding": "utf-8"
         }
         data = {
             "text": kwargs['text'],
             "target_lang": kwargs['to_language']
         }
-        return requests.post(url, headers=headers, data=data).json()["translations"][0]["text"]
+        return requests.post(url, headers=headers, data=data).json()["translations"][0]["text"]