Merge pull request #32555 from laravel/fix-boolean-value-assert-errors

[6.x] Fix boolean value in assertSessionHasErrors

src/Illuminate/Foundation/Testing/TestResponse.php

@@ -1029,7 +1029,7 @@ public function assertSessionHasErrors($keys = [], $format = null, $errorBag = '
             if (is_int($key)) {
                 PHPUnit::assertTrue($errors->has($value), "Session missing error: $value");
             } else {
-                PHPUnit::assertContains($value, $errors->get($key, $format));
+                PHPUnit::assertContains(is_bool($value) ? (string) $value : $value, $errors->get($key, $format));
             }
         }