Update dr_flac to 0.12.42 (#2798)

packages/d/dr_flac/xmake.lua

@@ -5,6 +5,7 @@ package("dr_flac")
     set_license("MIT")
 
     set_urls("https://github.com/mackron/dr_libs.git")
+    add_versions("0.12.42", "39ce69188eab79a913aa23423eef9da5f3dcd142")
     add_versions("0.12.41", "056b6f5e1f7cc5046aac33e6331551b6b2813292")
     add_versions("0.12.39", "7d3638f215599e4b576fe5d4be4f6820b9988e48")
     add_versions("0.12.29", "343aa923439e59e7a9f7726f70edc77a4500bdec")