Updated Flutter driver to version 2.18.1

Author: budtmo

Appium/Dockerfile

@@ -144,7 +144,7 @@ USER 1300:1301
 # Install basic Android drivers
 #===============================
 ENV APPIUM_DRIVER_ESPRESSO_VERSION="4.1.15"
-ENV APPIUM_DRIVER_FLUTTER_VERSION="2.17.0"
+ENV APPIUM_DRIVER_FLUTTER_VERSION="2.18.1"
 ENV APPIUM_DRIVER_FLUTTER_INTEGRATION_VERSION="1.2.0"
 ENV APPIUM_DRIVER_GECKO_VERSION="1.4.3"
 ENV APPIUM_DRIVER_UIAUTOMATOR2_VERSION="4.2.3"