test(render_points): regenerate baselines for scalar-colour scatter

The uniform-colour scalar `color=` path produces a sub-pixel edge-antialiasing
difference vs the previous per-point `c=` array (markers identical in position,
size, and colour). Two single-colour matplotlib stacking baselines exceeded
TOL=15 on their few large markers; regenerated from CI. Diff is edge-only
(verified), not a rendering change.

Author: timtreis