fix: minimize deps for docs.rs build

We don't need the rustls backends, since the docs only really need the
api, not the providers.

Fixes: #49

Author: tmccombs

Cargo.toml

@@ -66,10 +66,6 @@ path = "examples/http-change-certificate.rs"
 [package.metadata.docs.rs]
 features = [
     "rustls-core",
-    "rustls",
-    "rustls-aws-lc",
-    "rustls-fips",
-    "rustls-ring",
     "native-tls",
     "openssl",
     "rt"