Unnecessary delay if deserializeJson fails

[niclask]

Hi,

I was reading your code as I am considering using it for one of my projects. I spotted a delay in esp32FOTA::execHTTPcheck(...) that can cause problems for other people using you library. If deserializing JSON fails, it will halt the execution for 5 seconds. This will starve the execution of any other code and can lead to a critical failure (e.g. when controlling a motor).

See the code at:

esp32FOTA/src/esp32fota.cpp

Line 341 in 6648c9d

delay(5000);

[thorrak]

This was resolved in #72 and can be closed