write-fonts 0.54.0, read-fonts 0.45.0, skrifa 0.48.0. write-fonts now
computes the cmap14 length itself, and compute_delta returns an Option.

This also picks up the extension lookup fixes that let Source Serif 4
Variable compile.

An InsertionPoint's priority was the marker's byte offset in the source,
which could cause merges to fail when identical markers were in different
byte positions. With this patch the priority is the marker's index among the
source's markers.

[fea-rs] Order insert markers by index, not byte offset

Update fontations