Added header to fix build error

“Malcolm · “Malcolm · commit 2c0c768602d3 · 2025-07-26T00:58:50.000-04:00
diff --git a/src/mbgl/plugin/plugin_style_filter.hpp b/src/mbgl/plugin/plugin_style_filter.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <mbgl/storage/response.hpp>
+#include <functional>
 
 namespace mbgl {
 
