patch 8.1.0993: ch_read() may return garbage if terminating NL is missing

Problem:    ch_read() may return garbage if terminating NL is missing.
Solution:   Add terminating NUL. (Ozaki Kiichi, closes #4065)
diff --git a/src/version.c b/src/version.c
index 4ac981e..8722a83 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    993,
+/**/
     992,
 /**/
     991,