patch 8.2.2512: Vim9: compiling error test sometimes fails

Problem:    Vim9: compiling error test sometimes fails.
Solution:   use WaitForAssert() instead of sleeping for a bit. (Dominique
            Pellé, closes #7837)
diff --git a/src/version.c b/src/version.c
index c911822..dabc2af 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2512,
+/**/
     2511,
 /**/
     2510,