patch 9.0.1257: code style is not check in test scripts

Problem:    Code style is not check in test scripts.
Solution:   Add basic code style check for test files.
diff --git a/src/testdir/keycode_check.vim b/src/testdir/keycode_check.vim
index 6ad7b77..8320341 100644
--- a/src/testdir/keycode_check.vim
+++ b/src/testdir/keycode_check.vim
@@ -4,8 +4,8 @@
 #
 # Usage:  vim -u NONE -S keycode_check.vim
 #
-# Author: 	Bram Moolenaar
-# Last Update: 	2022 Nov 15
+# Author:	Bram Moolenaar
+# Last Update:	2022 Nov 15
 #
 # The codes are stored in the file "keycode_check.json", so that you can
 # compare the results of various terminals.
@@ -449,7 +449,7 @@
 # The main loop
 while true
   var action = inputlist(['Select operation:',
-    			'1. List results',
+			'1. List results',
 			'2. Add results for a new terminal',
 			'3. Replace results',
 			'4. Clear results',