Bump fontanf/shape dependency

[fontanf]

Bumps shape from ea5dc54 to b347249, which picks up fontanf/shape#69, fontanf/shape#70, fontanf/shape#71, fontanf/shape#72 and fontanf/shape#73.

Fixes #595 and #598.

What the new shape commits fix

• Fix degenerate line segment at the end of an on-circle arc approximation shape#69: the line-segment approximation of an arc placed on its circle ended with a degenerate segment, making circular holes look self-intersecting (irregular: "face area is not positive" when an outline arc is concentric with a circular hole #595).
• Fix orientation of the inner circular arc extras shape#70: the fallback union of that approximation used clockwise extras for anticlockwise arcs, filling holes.
• Treat a line as tangent to a circle when its closest point is on the circle shape#71 and Treat two circles as tangent when the midpoint of their intersections is on both shape#72: line/circle and circle/circle tangencies were computed as two intersections a few micro-units apart, or as none, which made boolean operations fail ("face area is not positive") or overflow the stack.
• Merge tied, nearly parallel plain edges in their exact order in no_fit_polygon shape#73: no_fit_polygon merged nearly parallel edges in the wrong order, so the self-NFPs used by the periodic packing were not exact, nor centrally symmetric. The lattice search unions then failed or crashed (Irregular: instance building aborts or segfaults with item spacing > 0 and more than 16 copies (arc handling in shape's boolean operations) #598).

Testing

With packingsolver built against shape at b347249:

• Unit tests pass for the three problem types that use shape: irregular (63), rectangle (145), rectangleguillotine (296).
• irregular: "face area is not positive" when an outline arc is concentric with a circular hole #595: the reported instance, and its variants rounded to 2, 3, 4 and 6 decimals, solve (both items packed). With the currently pinned shape, the instance building throws "face area is not positive".
• Irregular: instance building aborts or segfaults with item spacing > 0 and more than 16 copies (arc handling in shape's boolean operations) #598: instances A, B and C, and 19 random perturbations of each (vertices moved by up to 1e-5), all solve: 60/60. With the currently pinned shape, 36/60 solve.