Updated embedded `tx` to latest afdko version v4.0.1
0.2.8
Updated embedded AFDKO submodule to latest version 3.6.1. Removed no longer needed workaround for 13.
0.2.7
Remove deprecated FontMatrix operator left by tx in CFF2 FontDict when a font has non-standard UPEM, which produced a spurious warning when compiling with fonttools (13, 14).
0.2.6
*Really* fix issue with Python 3.7 on Windows this time...
0.2.5
Fixed issue on Windows Python 3.7+ whereby embedded tx.exe could not be found (12).