patch 9.1.0623: Mingw: errors when trying to delete non-existing files

Problem:  Mingw: warnings when trying to delete non-existing files
Solution: Use "rm -f" instead of "rm" to suppress errors for
          non-existing files (Ken Takata)

closes: #15350

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 01aea1f..e16ad29 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    623,
+/**/
     622,
 /**/
     621,