patch 9.1.1337: Undo corrupted with 'completeopt' "preinsert" when switching buffer

Problem:  Undo corrupted with 'completeopt' "preinsert" when switching
          buffer or window.
Solution: Do not delete preinsert text when switching buffer or window.
          (zeertzjq)

related: neovim/neovim#33581
closes: #17193

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 6d3a295..fec0e0d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1337,
+/**/
     1336,
 /**/
     1335,