Fix PDF export error by upgrading weasyprint from 60.2 to 68.0

- Fixed version incompatibility between weasyprint 60.2 and pydyf 0.12.1
- pydyf 0.12.1 changed PDF.__init__() to only accept 1 positional argument
- weasyprint 68.0 is compatible with current pydyf version
- Updated requirements.txt to reflect new weasyprint version

requirements.txt

@@ -21,4 +21,4 @@ click==8.1.7
 colorlog==6.8.2
 marshmallow==3.23.1
 redis==5.2.0
-weasyprint==60.2
\ No newline at end of file
+weasyprint==68.0
\ No newline at end of file