Remove feature rpk from hyper-boring and tokio-boring

Feature rpk in boring doesn't do anything unless you
explicitly use `SslAcceptor::rpk` or `SslContext::rpk_builder`,
and neither of these types are directly reachable if the
user depends only on tokio-boring or hyper-boring, which
means you still need to explicitly depend on the boring crate
to use RPK, in which case you can enable the feature there.

hyper-boring/Cargo.toml

@@ -25,9 +25,6 @@ fips = ["tokio-boring/fips"]
 # Link with precompiled FIPS-validated `bcm.o` module.
 fips-link-precompiled = ["tokio-boring/fips-link-precompiled"]
 
-# Enables Raw public key API (https://datatracker.ietf.org/doc/html/rfc7250)
-rpk = ["tokio-boring/rpk"]
-
 # Enables experimental post-quantum crypto (https://blog.cloudflare.com/post-quantum-for-all/)
 pq-experimental = ["tokio-boring/pq-experimental"]
 
@@ -39,7 +36,6 @@ pq-experimental = ["tokio-boring/pq-experimental"]
 # already containing required patches.
 no-patches = ["tokio-boring/no-patches"]
 
-
 [dependencies]
 antidote = { workspace = true }
 http = { workspace = true }

tokio-boring/Cargo.toml

@@ -22,9 +22,6 @@ fips = ["boring/fips", "boring-sys/fips"]
 # Link with precompiled FIPS-validated `bcm.o` module.
 fips-link-precompiled = ["boring/fips-link-precompiled", "boring-sys/fips-link-precompiled"]
 
-# Enables Raw public key API (https://datatracker.ietf.org/doc/html/rfc7250)
-rpk = ["boring/rpk"]
-
 # Enables experimental post-quantum crypto (https://blog.cloudflare.com/post-quantum-for-all/)
 pq-experimental = ["boring/pq-experimental"]