patch 8.1.1956: screenshot tests may use a different encoding

Problem:    Screenshot tests may use a different encoding. (Dominique Pelle)
Solution:   Always set 'encoding' to "utf-8" when running Vim in a terminal.
            (closes #4884)

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1956,
 /**/
     1955,
 /**/