Remove UnixTime Converter, it's broken

UnixTime Converter returns http code 522 when accessed

README.md

@@ -357,7 +357,6 @@ API | Description | Auth | HTTPS | CORS |
 | [Non-Working Days](https://isdayoff.ru) | Simple REST API for checking working, non-working or short days for Russia, CIS, USA and other | No | Yes | Yes |
 | [Russian Calendar](https://github.com/egno/work-calendar) | Check if a date is a Russian holiday or not | No | Yes | No |
 | [UK Bank Holidays](https://www.gov.uk/bank-holidays.json) | Bank holidays in England and Wales, Scotland and Northern Ireland | No | Yes | Unknown |
-| [UnixTime Converter](https://unixtime.co.za) | A REST API to convert UnixTime to DateTime and DateTime to UnixTime | No | Yes | Unknown |
 
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