Replace lockfree with lock_freedom

[jayvdb]

See rustsec/advisory-db#2214

[jayvdb]

ping @hulxv

[hulxv]

Hey @jayvdb, Thanks for informing me about this. as I see, lock_freedom doesn't have a lot of difference between it and lockfree. Are not there better alternatives? Our usage only for lock-free maps, nothing more.

Thanks again for your contribution and sorry for late response

[jayvdb]

I have not found a lockfree alternative that is only a map.
lock_freedom is just a slightly improved and maintained fork of lockfree, so that cargo audit/deny/etc do not complain about unmaintained crate.

[hulxv]

Okay, that's fine. it LGTM. Really thanks for your contribution