chore(Cargo.lock): update to qlog v0.15.2 (#2572)

`qlog` `v0.15.1` introduced various unnecessary dependencies. See
`Cargo.lock` changes in #2512 and
full analysis in cloudflare/quiche#2005.

This commit updates Neqo `Cargo.lock` to use `qlog` `v0.15.2`,
effectively removing all the unnecessary dependencies.

Given that Neqo builds with `qlog` `v0.15.1` just fine, this commit
updates the `Cargo.lock` only. Also note that this commit is not
required for `qlog` `v0.15.2` to land in mozilla-central.

Author: mxinden