LibGfx/PortableFormat: Remove PortableImageDecoderPlugin::initialize()

Author: https://github.com/LucasChollet
Commit: e72293fbc7
Pull-request: https://github.com/SerenityOS/serenity/pull/19932
Reviewed-by: https://github.com/AtkinsSJ ✅

Userland/Libraries/LibGfx/ImageFormats/PortableImageMapLoader.h

@@ -64,7 +64,6 @@ public:
 
     virtual IntSize size() override;
 
-    virtual ErrorOr<void> initialize() override { return {}; }
     virtual bool is_animated() override;
     virtual size_t loop_count() override;
     virtual size_t frame_count() override;