Update AsyncUDP library.json (#2837)

* Fix https://github.com/platformio/platform-espressif32/issues/186

* Drop library.json

libraries/AsyncUDP/library.json

-{
-  "name":"AsyncUDP",
-  "description":"Asynchronous UDP Library for ESP32",
-  "keywords":"async,udp,server,client,multicast,broadcast",
-  "authors":
-  {
-    "name": "Hristo Gochkov",
-    "maintainer": true
-  },
-  "repository":
-  {
-    "type": "git",
-    "url": "https://github.com/me-no-dev/ESPAsyncUDP.git"
-  },
-  "frameworks": "arduino",
-  "platforms":"espressif"
-}