migrate to clap 3.x

Bug: 229854484
Test: atest
Change-Id: Iae1ad1b5f7c2832c11bf2db09e7985ddaaf927d4
diff --git a/avmd/src/main.rs b/avmd/src/main.rs
index b156a66..ca28f42 100644
--- a/avmd/src/main.rs
+++ b/avmd/src/main.rs
@@ -149,8 +149,8 @@
 
     let args = app.get_matches();
     match args.subcommand() {
-        ("create", Some(sub_args)) => create(sub_args)?,
-        ("dump", Some(sub_args)) => dump(sub_args)?,
+        Some(("create", sub_args)) => create(sub_args)?,
+        Some(("dump", sub_args)) => dump(sub_args)?,
         _ => bail!("Invalid arguments"),
     }
     Ok(())