Update to janus 0.13.0

[vincentfretin]

Required changes in the C to Rust binding networked-aframe/janus-plugin-rs#2

Maintenance updates:

• libwebsockets from 3.2.3 to 4.3.2 done in 34ee2da
• libsrtp from 2.3.0 to 2.4.2 done in 34ee2da
• janus-gateway from v0.11.8 to v0.13.0

from the janus-gateway changelog, entries that may be relevant to our sfu plugin:

[v0.13.0] - 2022-10-03
- Switched to SHA256 for signing self signed DTLS certificates (thanks @tgabi333!) [https://github.com/meetecho/janus-gateway/pull/3069]
- Started using strnlen to optimize performance of some strlen calls (thanks @tmatth!) [https://github.com/meetecho/janus-gateway/pull/3061]
[v0.12.3] - 2022-06-20
- Keep track of RTP extensions when storing packets for retransmission [https://github.com/meetecho/janus-gateway/pull/2981]
[v0.12.2] - 2022-05-23
- Abort DTLS handshake if DTLSv1_handle_timeout returns an error
[v0.12.1] - 2022-04-26
- Fix highest sequence number not being properly initialized in the RTCP context [https://github.com/meetecho/janus-gateway/issues/2920]
- Reset rids when renegotiating SDPs [https://github.com/meetecho/janus-gateway/pull/2931]

[vincentfretin]

I froze the janus-plugin-sfu version to a specific commit after merging this PR 51394c9