Do not allow non-printable characters.

tests/vufind.php_cs

@@ -56,6 +56,7 @@ $rules = [
     'no_useless_return' => true,
     'no_whitespace_before_comma_in_array' => true,
     'no_whitespace_in_blank_line' => true,
+    'non_printable_character' => true,
     'ordered_imports' => true,
     'phpdoc_no_access' => true,
     'single_blank_line_at_eof' => true,

tests/vufind_templates.php_cs

@@ -50,6 +50,7 @@ $rules = [
     'no_useless_return' => true,
     'no_whitespace_before_comma_in_array' => true,
     'no_whitespace_in_blank_line' => true,
+    'non_printable_character' => true,
     'ordered_imports' => true,
     'phpdoc_no_access' => true,
     'single_blank_line_at_eof' => true,