[release_7] update latest api version and fix constructor

[xJuvi]

Update the API to the latest dev version and fix constructor loading for ILIAS7 support. (fixes #45 )

[waddahadel]

Hey @xJuvi ,

sorry for the late reply, this fix is valid, there is some slight mistake with the setDuration method in the CreateMeetingParameters, I was getting this error ilErrorHandling::{closure}:50 0 Argument 1 passed to BigBlueButton\Parameters\CreateMeetingParameters::setDuration() must be of the type int, null given just changed the expected type to ?int to allow more flexibility, I will merge and just fix it afterwards, nothing serious really, thanks for the help, I'm still a junior with PHP and ILIAS in particular, hope to get better with time