Allow string for Request data

[franmomu]

Looking at the Client::request:

Elastica/src/Client.php

Lines 500 to 509 in 682b78d

	* @param array|string $data OPTIONAL Arguments as array or pre-encoded string
	* @param array $query OPTIONAL Query params
	* @param string $contentType Content-Type sent with this request
	*
	* @throws Exception\ClientException|Exception\ConnectionException
	*/
	public function request(string $path, string $method = Request::GET, $data = [], array $query = [], string $contentType = Request::DEFAULT_CONTENT_TYPE): Response
	{
	$connection = $this->getConnection();
	$request = $this->_lastRequest = new Request($path, $method, $data, $query, $connection, $contentType);

It uses array|string for the data that is passed to Request.

And also in Http transport:

Elastica/src/Transport/Http.php

Lines 120 to 137 in 682b78d

	$data = $request->getData();
	$httpMethod = $request->getMethod();
	$headers[] = 'Content-Type: '.$request->getContentType();
	if (!empty($data)) {
	if ($this->hasParam('postWithRequestBody') && true == $this->getParam('postWithRequestBody')) {
	$httpMethod = Request::POST;
	}
	if (\is_array($data)) {
	$content = JSON::stringify($data, \JSON_UNESCAPED_UNICODE | \JSON_UNESCAPED_SLASHES);
	} else {
	$content = $data;
	// Escaping of / not necessary. Causes problems in base64 encoding of files
	$content = \str_replace('\/', '/', $content);
	}

It treats data as a string|array.

PHPStan found this at level 4:

 ------ -----------------------------------------------------------------------
  Line   src/Transport/Http.php
 ------ -----------------------------------------------------------------------
  132    Else branch is unreachable because previous condition is always true.
 ------ -----------------------------------------------------------------------