Remove "City, Warsaw Open Data", it's broken

README.md

@@ -1026,7 +1026,6 @@ API | Description | Auth | HTTPS | CORS |
 | [City, New York Open Data](https://opendata.cityofnewyork.us/) | New York (US) City Open Data | No | Yes | Unknown |
 | [City, Prague Open Data](http://opendata.praha.eu/en) | Prague(CZ) City Open Data | No | No | Unknown |
 | [City, Toronto Open Data](https://open.toronto.ca/) | Toronto (CA) City Open Data | No | Yes | Yes |
-| [City, Warsaw Open Data](https://api.um.warszawa.pl/) | Warsaw (PL) City Open Data | `apiKey` | Yes | Unknown |
 | [Code.gov](https://code.gov) | The primary platform for Open Source and code sharing for the U.S. Federal Government | `apiKey` | Yes | Unknown |
 | [Colorado Information Marketplace](https://data.colorado.gov/) | Colorado State Government Open Data | No | Yes | Unknown |
 | [Data USA](https://datausa.io/about/api/) | US Public Data | No | Yes | Unknown |