Unlike the rest of the crates, these don't have a "tor-" or "arti-"
prefix, and are potentially used by code outside arti.  With that in
mind, it's probably for the best not to bump them to 0.2.0 along
with the rest of our crates.

They have had no changes since 0.1.0 other than refactoring and
changing of clippy lints.  Therefore, I'm not bumping the
dependencies from other crates onto these: it's fine whether our
other crates use caret/retry-error 0.1.0 or 0.1.1.