remove opencv dependency warning

[knmcguire]

Now we have removed this issue: bitcraze/crazyflie-clients-python#611, we should remove notions of opencv problems in these repo docs: https://www.bitcraze.io/documentation/repository/aideck-gap8-examples/master/test-functions/wifi-streamer/ and the aideck tutorial https://www.bitcraze.io/documentation/tutorials/getting-started-with-aideck/ once we have a new release of the cfclient.