Bump lib version (me-no-dev#91)

Author: lobradov

library.json

@@ -12,7 +12,7 @@
     "type": "git",
     "url": "https://github.com/me-no-dev/ESPAsyncTCP.git"
   },
-  "version": "1.1.3",
+  "version": "1.2.0",
   "license": "LGPL-3.0",
   "frameworks": "arduino",
   "platforms": "espressif8266",