patch 9.1.0569: fnamemodify() treats ".." and "../" differently

Problem:  fnamemodify() treats ".." and "../" differently.
Solution: Expand ".." properly like how "/.." is treated in 8.2.3388.
          (zeertzjq)

closes: #15218

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 3b4cca6..4c6ed99 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    569,
+/**/
     568,
 /**/
     567,