Update some examples

[programatik29]

Motivation

Up to date examples are good.

Solution

• Update axum_server dependency in tls-rustls example.
• Tidy up low-level-rustls and chat examples.

[programatik29]

axum-server MSRV is 1.52.1.

[davidpdrsn]

@programatik29 wanna look at the CI errors?

[programatik29]

@programatik29 wanna look at the CI errors?

It is caused because axum-server version 0.2 msrv is 1.52.1 while axum msrv is 1.51 .

[davidpdrsn]

@programatik29 I found a fix for axum-server on 1.51 programatik29/axum-server#20

[programatik29]

I will merge it tomorrow.

[programatik29]

Your fix worked.