feat: update embedded-nal to 0.9

[Ddystopia]

No description provided.

[jordens]

Thanks for the contribution!

• Changelog entry regarding the NAL API bump
• Changelog entry about the MSRV change implied

Do you plan on porting https://github.com/quartiq/smoltcp-nal as well?

[Ddystopia]

I added changelog note about embedded-nal. Not sure what should I do about MSRV, as I can't find any previous mentions of it in this crate.

[Ddystopia]

By the way, smlang-rs is 0.6.0 in this project, but at 0.7.0 they made StateMachine::new and StateMachine::new_with_state const functions. This will allow Minimq::new become const too, as the rest of ecosystem has it's constructors. Current vertion om smlang is 0.8.0.

But smlang had breaking changes so it may not be worth it.

[Ddystopia]

Do you plan on porting https://github.com/quartiq/smoltcp-nal as well?

If this is a requirement for merging this then yes.

[jordens]

• Could you add a changelog entry about the minimum required rust version due to ip-in-core?
• Feel free to bump smlang in another PR and make the constructor const! PR appreciated. We use 0.8 downstream in miniconf as well.
• The smoltcp-nal bump isn't required but appreciated as currently it's probably one of the most prominent downstream crates.