Local file read and SSRF via fetcher bypass

SSRF in Kozea WeasyPrint before 70.0 allows remote attackers to read local files or load internal resources through PDF options. write_pdf() passes xmp_metadata to select_source() and creates CSS objects for stylesheets without the document's restrictive url_fetcher, so the default fetcher handles attacker-controlled paths and URLs. Exploitation requires a server-side application to configure a restrictive fetcher and forward attacker-influenced xmp_metadata or stylesheets values; the former embeds readable file bytes, while the latter loads and applies resources.