patch 8.1.0681: text properties as not adjusted for deleted text

Problem:    Text properties as not adjusted for deleted text.
Solution:   Adjust text properties when backspacing to delete text.
diff --git a/src/version.c b/src/version.c
index 8dcd56f..cd5e386 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    681,
+/**/
     680,
 /**/
     679,