Bump version to 2.1.0

Author: jesserockz

library.json

@@ -12,7 +12,7 @@
     "type": "git",
     "url": "https://github.com/esphome/ESPAsyncWebServer.git"
   },
-  "version": "2.0.1",
+  "version": "2.1.0",
   "license": "LGPL-3.0",
   "frameworks": "arduino",
   "platforms": ["espressif8266", "espressif32"],