patch 8.1.0638: text property highlighting is off by one column

Problem:    Text property highlighting is off by one column. (Bjorn Linse)
Solution:   Update text property highlighting earlier.  Let it overrule syntax
            highlighting.
diff --git a/src/version.c b/src/version.c
index c51a46d..5cffe09 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    638,
+/**/
     637,
 /**/
     636,