patch 8.1.0907: CI tests on AppVeyor are failing

Problem:    CI tests on AppVeyor are failing.
Solution:   Reduce the recursiveness limit for regexp.
diff --git a/src/version.c b/src/version.c
index 3a71b93..a66e8b6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    907,
+/**/
     906,
 /**/
     905,