Make a dependency on hyper optional

This commit addresses #3026 (comment)

rust-runtime/aws-smithy-http/Cargo.toml

@@ -11,8 +11,9 @@ license = "Apache-2.0"
 repository = "https://github.com/awslabs/smithy-rs"
 
 [features]
+hyper014 = ["dep:hyper"]
+event-stream = ["aws-smithy-eventstream", 'hyper014']
 rt-tokio = ["aws-smithy-types/rt-tokio"]
-event-stream = ["aws-smithy-eventstream"]
 
 [dependencies]
 aws-smithy-eventstream = { path = "../aws-smithy-eventstream", optional = true }
@@ -27,9 +28,11 @@ pin-project-lite = "0.2.9"
 pin-utils = "0.1.0"
 tracing = "0.1"
 
-# For our event stream implementation
+# For an adapter to enable the `Stream` trait for `aws_smithy_types::byte_stream::ByteStream`
 futures-core = "0.3.14"
-hyper = "0.14.26"
+
+# For our event stream implementation
+hyper = { version = "0.14.26", optional = true }
 
 [dev-dependencies]
 async-stream = "0.3"