Compatible with Laravel-8 and update requirements | new version + support new zarinpal system Authority code

[mrajaeim]

Compatible with Laravel-8 and update requirements
Replace abandoned satooshi/php-coveralls with php-coveralls/php-coveralls

[mrajaeim]

How to use this fork as zarinpal/zarinpal

• Fork THIS repository and add this code to your composer.json

"repositories": [
        {
            "type": "vcs",
            "url":"https://github.com/<Your_GitHub_Username>/zarinpal-composer-library"
        }
    ],

• Append "zarinpal/zarinpal": "dev-master" to "require"
• Execute command composer update
• Generate GitHub Token key (open link that printed in console by composer for token generating)
• Enter Token and Done!

[mrajaeim]

In latest commit I changed code to support new Zarinpal Authority code system