Update ESPAsyncTCP to 7e9ed22 (#1752, #1806)

Fix random resets when connection closes prematurely

code/platformio.ini

@@ -87,7 +87,7 @@ lib_deps =
     https://github.com/xoseperez/eeprom_rotate#0.9.2
     Embedis
     https://github.com/plerup/espsoftwareserial#3.4.1
-    https://github.com/me-no-dev/ESPAsyncTCP#55cd520
+    https://github.com/me-no-dev/ESPAsyncTCP#7e9ed22
     https://github.com/me-no-dev/ESPAsyncWebServer#05306e4
     https://bitbucket.org/xoseperez/fauxmoesp.git#3.1.0
     https://github.com/xoseperez/hlw8012.git#1.1.0