Fix regexify escape backslash in character class (#434)

* TASK: fix regexify backslash in character class

Author: krsriq

Diff for: src/Faker/Provider/Base.php

@@ -525,7 +525,9 @@ public static function regexify($regex = '')
         }, $regex);
         // All [ABC] become B (or A or C)
         $regex = preg_replace_callback('/\[([^\]]+)\]/', static function ($matches) {
-            $randomElement = Base::randomElement(str_split($matches[1]));
+            // remove backslashes (that are not followed by another backslash) because they are escape characters
+            $match = preg_replace('/\\\(?!\\\)/', '', $matches[1]);
+            $randomElement = Base::randomElement(str_split($match));
             //[.] should not be a random character, but a literal .
             return str_replace('.', '\.', $randomElement);
         }, $regex);

Diff for: test/Faker/Provider/BaseTest.php

@@ -333,6 +333,7 @@ public function regexifyDataProvider()
             ['[aeiou]', 'basic character class'],
             ['[a-z]', 'character class range'],
             ['[a-z1-9]', 'multiple character class range'],
+            ['[a-z\-]{4}', 'character class range with quantifier and escaped character'],
             ['a*b+c?', 'single character quantifiers'],
             ['a{2}', 'brackets quantifiers'],
             ['a{2,3}', 'min-max brackets quantifiers'],