Do not use object return type hint

[sergeyklay]

Hello!

• Type: bug fix
• Link to issue: [BUG]: object return type hint leads to fatal error #14987

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Fixed return type hints for the following methods:

• Phalcon\Dispatcher\AbstractDispatcher::dispatch
• Phalcon\Dispatcher\DispatcherInterface::dispatch
• Phalcon\Filter::get
• Phalcon\Http\Message\AbstractCommon::cloneInstance
• Phalcon\Http\Message\AbstractCommon::processWith
• Phalcon\Http\Message\AbstractMessage::withAddedHeader
• Phalcon\Http\Message\AbstractMessage::withBody
• Phalcon\Http\Message\AbstractMessage::withHeader
• Phalcon\Http\Message\AbstractMessage::withProtocolVersion
• Phalcon\Http\Message\AbstractMessage::withoutHeader
• Phalcon\Http\Message\AbstractRequest::withMethod
• Phalcon\Http\Message\AbstractRequest::withRequestTarget
• Phalcon\Http\Message\AbstractRequest::withUri
• Phalcon\Mvc\Model\Binder::findBoundModel
• Phalcon\Validation::getEntity
• Phalcon\Validation\ValidationInterface::getEntity

Thanks