Symfony 3.4.41

What's new in this version:

- [Validator] never directly validate Existence (Required/Optional) constraints
- [Console] Fix QuestionHelper::disableStty()
- [Form] validate subforms in all validation groups
- Fixes sprintf(): Too few arguments in form transformer
- Add meaningful message when using ProcessHelper and Process is not installed
- Handle fetch mode deprecation of DBAL 2.11.
- [Security] Fixed handling of CSRF logout error
- [VarDumper] fix PHP 8 support
- [Cache] Accessing undefined constants raises an Error in php8
- Address deprecation of ReflectionType::getClass()
- [VarDumper] ReflectionFunction::isDisabled() is deprecated
- [Validator] Catch expected ValueError
- [DomCrawler] Catch expected ValueError
- [PropertyAccess] Parse php 8 TypeErrors correctly
- [Config] Removed implicit cast of ReflectionProperty to string
- [PhpUnitBridge] fix installing under PHP >= 8
- [HttpKernel] Fix that the Store would not save responses with the X-Content-Digest header present
- [PhpUnitBridge] fix bad detection of unsilenced deprecations
- [HttpKernel] Fix error logger when stderr is redirected to /dev/null
- [BrowserKit] Allow Referer set by history to be overridden
- [Serializer] fix issue with PHP 8
- [Yaml] Fix escaped quotes in quoted multi-line string
- [PhpUnitBridge] Mark parent class also covered in CoverageListener
- [Yaml] prevent notice for invalid octal numbers on PHP 7.4
- [Filesystem] Handle paths on different drives
- [WebProfiler] Do not add src-elem CSP directives if they do not exist
- [DX] Show the ParseException message in all YAML file loaders
- [Yaml] fix parse error when unindented collections contain a comment
- [Validator] Skip validation when email is an empty object
- [PhpUnitBridge] fix PHP 5.3 compat again
- [Validator] fix lazy property usage.
- [PhpUnitBridge] fix compat with PHP 5.3