Log Message:
py-fonttools: updated to 4.8.1

4.8.1 (released 2020-04-17)
---------------------------
- [feaLib] Fixed ``AttributeError: 'NoneType' has no attribute 'getAlternateGlyphs'``
  when ``aalt`` feature references a chain contextual substitution lookup

4.8.0 (released 2020-04-16)
---------------------------
- [feaLib] If Parser is initialized without a ``glyphNames`` parameter, it cannot
  distinguish between a glyph name containing an hyphen, or a range of glyph names;
  instead of raising an error, it now interprets them as literal glyph names, while
  also outputting a logging warning to alert user about the ambiguity
- [feaLib] When serializing AST to string, emit spaces around hyphens that denote
  ranges. Also, fixed an issue with CID ranges when round-tripping \ 
AST->string->AST
- [Snippets/otf2ttf] In otf2ttf.py script update LSB in hmtx to match xMin
- [colorLib] Added experimental support for building ``COLR`` v1 tables as per
  the `colr-gradients-spec \ 
<https://github.com/googlefonts/colr-gradients-spec/blob/master/colr-gradients-spec.md>`__
  draft proposal. **NOTE**: both the API and the XML dump of ``COLR`` v1 are
  susceptible to change while the proposal is being discussed and formalized