Fix Error: assigning to 'AVCodec *' from 'const AVCodec *' discards qualifiers in newer ffmpeg versions (#746)

Co-authored-by: Tomi Lähteenmäki <[email protected]>

Author: Dygear

rwengine/src/audio/SoundSource.hpp

@@ -90,7 +90,7 @@ class SoundSource {
     AVFrame* frame = nullptr;
     AVFormatContext* formatContext = nullptr;
     AVStream* audioStream = nullptr;
-    AVCodec* codec = nullptr;
+    const AVCodec* codec = nullptr;
     SwrContext* swr = nullptr;
     AVCodecContext* codecContext = nullptr;
     AVPacket readingPacket;