GHSA-c3jg-qh8m-j3h2: CairoSVG: Quadratic-time DoS parsing a crafted SVG

Rendering an untrusted SVG whose contains many segments is O(n²) CPU. A single under 1 MiB burns tens of seconds. Two independent O(n²) sites in cairosvg/path.py: 1. Tokenizer — the path-data parser consumes the d string with a while string: loop that repeatedly slices/re-scans the *remaining* string (each step is O(len remaining)), giving O(n²) over the whole attribute. 2. draw_markers — marker handling drains node.vertices with while node.vertices: ... node.vertices.pop(0); list.pop(0) is O(n), so draining n vertices is O(n²). …