patch 8.1.2251: ":term command" may not work without a shell

Problem:    ":term command" may not work without a shell.
Solution:   Add the ++shell option to :term. (closes #3340)
diff --git a/src/version.c b/src/version.c
index 5a4a1e4..767cbec 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2251,
+/**/
     2250,
 /**/
     2249,