Fix dependency issue

1.21

Update composer.json

Added support for PHP 8.0

Added support for PHP 8.0

Supported Guzzle versions updated

Supported Guzzle versions updated

Scrutinizer spacing patches, reorganize imports, reformat and clean code.

Scrutinizer spacing patches.
Reorganize imports, reformat and clean code.
Update OpenVidu.php.
Update Session.php.

Changes in the session constructor method

The optional sessionId parameter has been added to the Session class constructor to avoid creating a new session when you are actually trying to get an existing one. It currently duplicates the object to use the fromJson method to hydrate it.
Thanks to @lucianefalcao for the report

Changes to support Openvidu version 2.15

Changes to support Openvidu version 2.15.
Refactorings, Bug fixes and Improvements

Adaptation to Openvidu 2.13, 2.14

Adaptation for correct operation with Openvidu versions 2.13 and 2.14

Several corrections and improvements - Openvidu 2.13, 2.14

Several corrections and improvements made by @sobolevna

Added a method to check if session exists on cache - Openvidu 2.12, 2.13, 2.14

Added a method to check if a session exists on cache

Added existsSession(string $sessionId) method

Update documentation and remove unused code - Openvidu 2.12, 2.13

Reformat code and add scrutinizer-ci ignore-call for Illuminate\Foundation calls
Change facade method documentation to static
Improvements