Fix release workflow to leave php and ext-json requirements

[antonmedv]

Currently the package could be installed on PHP 7.2 (php7.2 /usr/bin/composer require deployer/deployer) as there are no version constraints, but will fail after running php7.2 vendor/bin/dep with error message Your Composer dependencies require a PHP version ">= 7.3.0"... (this error is generated by platform_check.php inside the PHAR).

That does not seem ideal to me, as in my opinion the package should at least require PHP version 7.3+ and ext-json to prevent installing it on older PHP version or with json extension disabled. The remaining dependencies symfony/*, psr/http-message etc. need not be required, as they are already packaged inside the PHAR.

Originally posted by @nufue in #3224 (reply in thread)