Hotfix: axum is obviously an optional dep

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "tokio-listener"
-version = "0.4.0"
+version = "0.4.1"
 edition = "2021"
 repository = "https://github.com/vi/tokio-listener"
 license = "MIT OR Apache-2.0"
@@ -31,7 +31,7 @@ tokio = { version = "1.29.1", features = ["net", "io-std", "time", "sync"] }
 tonic = { package = "tonic", version = "0.11.0", optional = true }
 tonic_010 = { package = "tonic", version = "0.10.2", optional = true }
 tracing = "0.1.37"
-axum07 = { version="0.7", package="axum" }
+axum07 = { version="0.7", package="axum", optional=true }
 futures-util = {version="0.3", optional=true}
 tokio-util = {version = "0.7", optional=true, features=["net","codec"]}
 
@@ -52,7 +52,7 @@ serde = ["dep:serde", "serde_with"]
 hyper014 = ["dep:hyper014"]
 
 ## Enable tokio-listener-adapted `serve` function from Axum 0.7 (and related types)
-axum07 = ["dep:hyper1", "dep:hyper-util", "dep:futures-util", "dep:tower-service", "dep:tower"]
+axum07 = ["dep:hyper1", "dep:hyper-util", "dep:futures-util", "dep:tower-service", "dep:tower", "dep:axum07"]
 
 ## Enable inetd (stdin/stdout) mode
 inetd = ["dep:futures-util"]