feat: add async support

Cargo.lock

@@ -273,13 +273,20 @@ dependencies = [
 
 [[package]]
 name = "pamsock"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "anstyle",
  "clap",
  "pam",
+ "tokio",
 ]
 
+[[package]]
+name = "pin-project-lite"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.106"
@@ -367,6 +374,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.49.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72a2903cd7736441aac9df9d7688bd0ce48edccaadf181c3b90be801e81d3d86"
+dependencies = [
+ "pin-project-lite",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.24"