Log Message:
py-weasyprint: updated to 51

Version 51

Dependencies:
Pyphen 0.9.1+ is now needed

New features:
* Add support of element() and running()
* Add HTML element to Box class
* Support larger and smaller values for font-size

Bug fixes:
* Fix how fonts used for macOS tests are installed
* Fix various crashes due to line breaking bugs
* Fix typo in variable name
* Don’t crash when string-set is set to none
* Keep font attributes when text lines are modified
* Don’t let presentational hints add decorations on tables with no borders
* Don’t crash on improper var() values
* Fix rendering of header and footer for empty tables
* Avoid quadratic time relative to tree depth when setting page names