make cargo dependencies less specific

          Can you reduce the specificity of the dependency versions? We have seen conflicts with other downstream dependencies at times when they require a "no-higher-than X" version.

async-recursion = "1"
async-trait = "0.1"
bytes = "1"
chrono = { version = "0.4", default-features = false, features = ["std", "alloc", "serde", "clock"] }
dyn-clone = "1"
futures = "0.3"
futures-core = "0.3"

_Originally posted by @webern in https://github.com/awslabs/tough/pull/687#discussion_r1382001643_

awslabs / tough

make cargo dependencies less specific #699