The package has been built and is here: https://salsa.debian.org/php-team/pear/php-svg-lib/
But it will only work with a more actual version of php-horde-css-parser. This package is in the horde-team section where I can't push, so version 8.4.0 is here: https://github.com/sunflowerbofh/PHP-CSS-Parser/tree/debian/8.4.0