Refresh native apt indexes before cross-build setup.

crates/bds-ui/tests/packaging_assets.rs

@@ -214,6 +214,13 @@ fn tagged_releases_are_built_and_packaged_with_rust_tools() {
     let native_python = linux_dependencies
         .find("install_packages python3 python3-typing-extensions")
         .expect("native Python dependency setup");
+    let native_source_filter = linux_dependencies
+        .find("'/^Architectures:/d; /^Types: deb$/a Architectures: arm64'")
+        .expect("native apt architecture filter");
+    assert!(
+        linux_dependencies[native_source_filter..native_python].contains("sudo apt-get update"),
+        "native apt indexes must be refreshed after constraining the source architecture"
+    );
     assert!(
         native_python < multiarch,
         "native Python dependencies must be fixed before enabling multiarch"