.github/workflows/build.yml: disable yajl on macOS

This yajl on Homebrew comes with broken headers:

 /opt/homebrew/Cellar/yajl/2.1.0/include/yajl/yajl_parse.h:22:10: fatal error: 'yajl/yajl_common.h' file not found
 #include <yajl/yajl_common.h>
          ^~~~~~~~~~~~~~~~~~~~

Author: MaxKellermann

.github/workflows/build.yml

@@ -122,7 +122,6 @@ jobs:
             googletest \
             icu4c \
             ffmpeg \
-            yajl \
             libupnp \
             libid3tag \
             chromaprint \