anchor.diff:  
   Compliance::
   
  -* drop support for versions of Asciidoctor < 2 (#1552)
   * drop support for Ruby < 2.5 (which includes JRuby 9.1) (#1681)
  -* release lock on ttfunk version (1.6 produces slightly different output from 1.5 for certain missing glyphs)
  -* upgrade to Prawn 2.3.0 (which adds OTF font support), then to Prawn 2.4.0
  -* upgrade to prawn-svg 0.32 (adds support for Ruby 3 without a patch and for loading embedded images from a data URI)
  -* upgrade to prawn-icon 3.0.x
   * use YAML.safe_load from Ruby stdlib instead of safe_yaml gem
   * drop deprecated Pdf module alias in API (leaving only PDF)
   * remove deprecated "ascii" fonts; only bundle the more complete "subset" fonts
  
positive.code: * add Ruby 3.1 to CI matrix; use as primary Ruby
  * test against Asciidoctor upstream (#1821)
  * skip tests for unreadable files when euid is 0
  * test against pygments.rb 2.0.0
  
  == 1.5.3 (2020-02-28) - @mojavelinux
  
  
negative.code: * do not crash if item in unordered description list has no desc and do not append subject stop to term
  * resolve images in theme correctly when theme is loaded from classloader (JRuby only) (#1829)
  * log warning rather than crash if front cover image cannot be embedded (such as a broken SVG)
  * do not insert blank line in index when term is forced to break (#1665)
  * honor prepress page margins on subsequent pages in index (#1929)
  * use more robust strategy for line height normalization that accounts for line contains only monospaced text (#1650)
  