h-gtk: Add resources/ to the cargo check list.

hammond-gtk/build.rs

@@ -1,6 +1,10 @@
 use std::process::Command;
 
 fn main() {
+    // Rerun the build script when files in the resources folder are changed.
+    println!("cargo:rerun-if-changed=resources");
+    println!("cargo:rerun-if-changed=resources/*");
+
     Command::new("glib-compile-resources")
         .args(&["--generate", "resources.xml"])
         .current_dir("resources")