patch 9.1.0757: tests: messages files contains ANSI escape sequences

Problem:  tests: messages files contains ANSI escape sequences
Solution: filter those out in runtests.vim

Also, since we are setting $LC_ALL, we don't need to set $LANG and
$LANGUAGE since those are overridden by $LC_ALL anyhow.

closes: #15788

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 633c1e6..2f01df8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    757,
+/**/
     756,
 /**/
     755,