Bump rustls and related crates to latest versions

[tnull]

Fixes #553.
Alternative to #536, which also bumps rustls-webpki and other related crates.

Since there have recently been some advisories, we bump rustls and related crates such as rustls-webpki to latest versions.

[luisschwab]

You could add a cargo audit CI job here as well.

[luisschwab]

You need to alllow the duplicate deps on bitreq's Cargo.toml to fix linting

[tnull]

You could add a cargo audit CI job here as well.

Eh, well, yes, see #557.

You need to alllow the duplicate deps on bitreq's Cargo.toml to fix linting

I'm aware, still trying to keep the duplicates minimal though, will update in abit.

[luisschwab]

@tcharding if we could get a new bitreq release after this is merged it would be great. Thanks.