patch 8.2.2959: sound_playfile() is not tested on MS-Windows

Problem:    sound_playfile() is not tested on MS-Windows.
Solution:   Make it work and enable the test. (Dominique Pellé, closes #8338)
diff --git a/src/version.c b/src/version.c
index e39ee98..13a5200 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2959,
+/**/
     2958,
 /**/
     2957,