Surge Editor: Remove unused private variable (#8216)

Author: RavenRandomz

src/surge-xt/SurgeSynthEditor.h

@@ -143,7 +143,6 @@ class SurgeSynthEditor : public juce::AudioProcessorEditor,
 
   private:
     std::unique_ptr<SurgeGUIEditor> sge;
-    std::unique_ptr<juce::Drawable> logo;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(SurgeSynthEditor)
 };