MSRV 1.72

[dfaust]

• Raise MSRV to 1.72
• Remove internal use of crossbeam because std::sync::mpsc::Sender implements Sync since version 1.72, so there is no need for crossbeam anymore
• Specify dependencies in workspace

I screwed up a bit and this PR is based on my previous on (#567).

[0xpr03]

Let's merge this with #568 as 7.0 and try to get everything else into 6.X

Or is there anything else that would be major breaking ?

[dfaust]

The change to the event serialization is already in main. And that's breaking.
I don't think releasing another 6.x version is worth the effort.

[0xpr03]

Ah yeah, my bad. Nevermind then, break all the things.

[0xpr03]

This also needs a rebase

[0xpr03]

I'll re-rebase this when I'm back at home (+2days!). Then I wall have to look at the outstanding issues and PR that accumulated over the past ~2 months and push the release finally over the line..

Thanks for all the work!

[dfaust]

Can we merge this? I already based my next PR on this one.