Upgrade rustls and quinn

According to RUSTSEC-2023-0052 we need to upgrade rustls to 0.21
to get a fix for the issue which may or may not affect Veloren
since it's about client certificates but with the absence of a
PoC it seems like a good idea to upgrade anyway, just to be sure.

webpki has gone unmaintained (which rustls 0.20 depends on),
starting with rustls 0.21 it depends on rustls-webpki which
contains a fix for the issue. Since quinn also depends on
rustls 0.20 in 0.8 and 0.9 versions, we needed to upgrade it to
0.10 so that it depends on rustls 0.21 which we now use.