Use SPAUDIO_DEPRECATED instead of the C++ attribute

Fixes compilation with GCC 12 and older.

Author: ePirat

include/AmbisonicProcessor.h

@@ -108,8 +108,9 @@ namespace spaudio {
      *  Please use AmbisonicRotator instead.
      */
 
-    class SPAUDIO_API
-        [[deprecated("This class is deprecated. Please use AmbisonicRotator class instead.")]]
+    class
+        SPAUDIO_DEPRECATED("This class is deprecated. Please use AmbisonicRotator class instead.")
+        SPAUDIO_API
     AmbisonicProcessor : public AmbisonicBase
     {
     public:

include/AmbisonicShelfFilters.h

@@ -26,8 +26,9 @@ namespace spaudio {
     /** This class applies frequency dependent basic & max-rE optimisation to a B-format signal using linear phase FIR filters.
      *  This class is deprecated in favour of AmbisonicOptimFilters, which uses LinkwitzRiley IIR filters to apply frequency dependent gains.
      */
-    class SPAUDIO_API
-        [[deprecated("This class is deprecated. Please use AmbisonicOptimFilters class instead.")]]
+    class
+        SPAUDIO_DEPRECATED("This class is deprecated. Please use AmbisonicOptimFilters class instead.")
+        SPAUDIO_API
     AmbisonicShelfFilters : public AmbisonicBase
     {
     public: