remove either rustls or rust-native

[hpk42]

core currently includes two TLS stacks, native and rustls. rust-native does not yet support async -- maybe @dignifiedquire could clarify how far that is away. reqwest (used by core) in turn does not support rustls -- not sure how far that is away. IMO the API of rust-native is much nicer than with rustls but that's not a big inconvenience at this point. We want to get rid of one of the TLS stacks, also to reduce size of the compiled lib which is shipped in the releases. See also #870 how the two-tls situation increases compile times etc. If one of the two stacks leads to a lesser increase in file size, i'd have a preference for that, at least in the longer term.

[dignifiedquire]

That is not quite correct, there is only rustls as of today, if you look at the Cargo.lock there is no refernce to openssl or native_tls

[hpk42]

ah k, i misunderstood then ... the fact that #870 (comment) is pending only means that we need to use an older version, which then duplicates dependencies but that's tracked in #870 . closing here.