patch 8.1.2112: build number for ConPTY is outdated

Problem:    Build number for ConPTY is outdated.
Solution:   Update to new build number. (Nobuhiro Takasaki, closes #5014)
diff --git a/src/version.c b/src/version.c
index f77ecc6..eb1ad1f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2112,
+/**/
     2111,
 /**/
     2110,