Update pid to u32

See https://github.com/aya-rs/aya/commit/1944c4aa008d685053bb617b728e3e.

{{project-name}}/src/main.rs

@@ -65,7 +65,7 @@ struct Opt {
     cgroup_path: std::path::PathBuf,
 {%- when "uprobe", "uretprobe" %}
     #[clap(short, long)]
-    pid: Option<i32>,
+    pid: Option<u32>,
 {%- endcase %}
 }