testing/janus-gateway: upgrade to 0.10.3

[v0.10.3] - 2020-07-09
Fixed occasional crashes in VideoRoom related to subscribers activity [PR-2236] [PR-2253]
Fixed AudioBridge compilation issues when libogg is missing (thanks @ffontaine!) [PR-2238]
Fixed broken SRTP forwarders in AudioBridge [PR-2258]
Fixed occasional segfaults due to race conditions in SIP plugin [PR-2247]
Fixed occasional recording issues in Janus and Duktape plugins
Added timeout (120s) on idle connections in HTTP transport
Fixed Opus recordings occasionally being way too large than the source file when processed via janus-pp-rec (thanks @neilkinnish!) [PR-2250]
Added a new web demo to use canvas elements as a media source for PeerConnections [PR-2261]
Other smaller fixes and improvements (thanks to all who contributed pull requests and reported issues!)