4.4.0

CHANGES:

• Fixes to odoc warnings and cohttp dependencies (@Aaylor #244)
• Support cohttp 4.0. (@tmcgilchrist #257)
• Support for 4.12 and fixing recent compiler warnings (@tmcgilchrist #246 #252 and @emillon #250 #247 #251)
• Add a new package github-data which contains just the serialisation logic
  without a dependency on the web stack (#248 @emillon)
• Add Github checks API support (#249 @tmcgilchrist)
• Label field missing in branch refs for ghost (@dra27 and @tmcgilchrist #256)
• Get all commits for user/repo (@Stevendeo #245)