chore(dependencies): update pin-project to 0.4.0-alpha.9

Author: taiki-e

Cargo.toml

@@ -32,8 +32,7 @@ iovec = "0.1"
 itoa = "0.4.1"
 log = "0.4"
 net2 = { version = "0.2.32", optional = true }
-pin-project = { version = "=0.4.0-alpha.7", features = ["project_attr"] }
-
+pin-project = { version = "=0.4.0-alpha.9", features = ["project_attr"] }
 time = "0.1"
 tokio = { version = "=0.2.0-alpha.4", optional = true, default-features = false, features = ["rt-full"] }
 tower-service = "=0.3.0-alpha.1"