Bump arduino-esp32 build to include core 1.0.4

We need this for the emptyString definition amongst other things.

Author: dirkmueller

airrohr-firmware/platformio.ini

@@ -83,7 +83,7 @@ extra_scripts = platformio_script.py
 # needs to be adjusted to the matching version from
 # https://github.com/platformio/platform-espressif8266/releases
 platform_version = [email protected]
-platform_version_esp32 = espressif32@1.9.0 ; using Arduino core 1.0.2
+platform_version_esp32 = espressif32@1.11.1 ; using Arduino core 1.0.4
 
 [env]
 ;lib_ldf_mode = chain+  ; automatically detect libraries by the used includes