Merge branch '6.0' into 6.1

* 6.0:
  [BrowserKit] Merge fields and files recursively if they are multidimensional array
  [String] Fix `width` method in `AbstractUnicodeString`
  [Mailer] Add a comment to avoid the same wrong PR over and over again
  [Serializer] Fix XmlEncoder encoding attribute false
  [HttpFoundation] Fix `\Stringable` support in `InputBag::get()`

Author: chalasr

Encoder/XmlEncoder.php

@@ -361,6 +361,9 @@ private function buildXml(\DOMNode $parentNode, mixed $data, string $format, arr
                     if (!\is_scalar($data)) {
                         $data = $this->serializer->normalize($data, $format, $context);
                     }
+                    if (\is_bool($data)) {
+                        $data = (int) $data;
+                    }
                     $parentNode->setAttribute($attributeName, $data);
                 } elseif ('#' === $key) {
                     $append = $this->selectNodeType($parentNode, $data, $format, $context);

Tests/Encoder/XmlEncoderTest.php

@@ -96,6 +96,13 @@ public function testAttributes()
             'föo_bär' => 'a',
             'Bar' => [1, 2, 3],
             'a' => 'b',
+            'scalars' => [
+                '@bool-true' => true,
+                '@bool-false' => false,
+                '@int' => 3,
+                '@float' => 3.4,
+                '@sring' => 'a',
+            ],
         ];
         $expected = '<?xml version="1.0"?>'."\n".
             '<response>'.
@@ -106,6 +113,7 @@ public function testAttributes()
             '<Bar>2</Bar>'.
             '<Bar>3</Bar>'.
             '<a>b</a>'.
+            '<scalars bool-true="1" bool-false="0" int="3" float="3.4" sring="a"/>'.
             '</response>'."\n";
         $this->assertEquals($expected, $this->encoder->encode($obj, 'xml'));
     }