[CodeQuality] Fix escape character on SimplifyRegexPatternRector part 2 (#7391)

Author: samsonasik

rules/CodeQuality/Rector/FuncCall/SimplifyRegexPatternRector.php

@@ -21,12 +21,12 @@ final class SimplifyRegexPatternRector extends AbstractRector
      * @var array<string, string>
      */
     private const COMPLEX_PATTERN_TO_SIMPLE = [
-        '[0-9]' => '\\d',
-        '[a-zA-Z0-9_]' => '\\w',
-        '[A-Za-z0-9_]' => '\\w',
-        '[0-9a-zA-Z_]' => '\\w',
-        '[0-9A-Za-z_]' => '\\w',
-        '[\r\n\t\f\v ]' => '\\s',
+        '[0-9]' => '\\\d',
+        '[a-zA-Z0-9_]' => '\\\w',
+        '[A-Za-z0-9_]' => '\\\w',
+        '[0-9a-zA-Z_]' => '\\\w',
+        '[0-9A-Za-z_]' => '\\\w',
+        '[\r\n\t\f\v ]' => '\\\s',
     ];
 
     public function __construct(