patch 8.1.2323: Old MSVC version no longer tested.

Problem:    Old MSVC version no longer tested.
Solution:   Drop support for MSCV 2008 and older. (Ken Takata, closes #5248)
diff --git a/src/version.c b/src/version.c
index fc61f42..4b5d180 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2323,
+/**/
     2322,
 /**/
     2321,