Change Docker image name:
	bc-dev-android:r20 -> bc-dev-android-r20:20210217_python3

(cherry picked from commit 22272cd7c60cf201ea58e6f4196e8df5c59eb4df)

Updated liblinphone to return at least once headset/headphones audio device if available in audioDevicesList

Fixed wrong directory when we are launching a different tester for the same commit-id
Fixed allure unique URL and alias for iOS tester

Set amplitude to 0 on dtmf generations. Stop file player to play a file when stopping tone is requested. Note that playfile has been call when incall.

Added debug output
Enabled allow-failure for report upload job since we now strictly check bash script errors

Fix cast as belle_sip_parameters_get_parameters returns a belle_sip_param_pair_t and not a const char* causing belle_sip_uri_equals_with_omission to return false negatives

Fix bug causing undesired transition from Paused to StreamsRunning state in case of incoming UPDATE request.

Fixed doc upload by retrieving patch version x.y.z of doc and putting it in x.y. Fixed macos and ios upload to upload in either snapshots or release directory based on git describe

created new image for android r20 docker tests (shoudl fix android test launch for nightly master), pushed image to the registry

Fix scheduled pipeline not run (bug due to disabled job in schedule need list, Gitlab 13.9.x), splitted windows tests by source build job

 - further implement RFC4575 media events
 - the conference sends out the conference capabilities in its full state notify
 - when the conference media change, a media event will be sent out to inform participants (onAvailableMediaChanged)
 - when a remote participant pauses its call and conference event package is enabled, a participant device media changed event is sent (onParticipantDeviceMediaChanged)
 - prevent that a core that supports the event conference package pauses individual calls in a conference
 - rework of address comparison using belle sip functions
 - add conference parameter to allow conference with one participant