Bump version to 3.2.1

Author: jesserockz

library.json

@@ -12,7 +12,7 @@
  "type": "git",
  "url": "https://github.com/esphome/ESPAsyncWebServer.git"
  },
- "version": "3.2.0",
+ "version": "3.2.1",
  "license": "LGPL-3.0",
  "frameworks": "arduino",
  "platforms": ["espressif8266", "espressif32", "libretiny"],