head-checking: update changelog

--HG--
branch : stable
7 jobs for topic/stable/fix-heads.pre-check.mixed in 6 minutes and 25 seconds (queued for 39 seconds)
Status Job ID Name Coverage
  Test
passed doc #67258

00:01:52

passed flake8 #67252

00:00:53

manual pytype #67253
allowed to fail manual
passed tests-py2-cext #67254

00:05:19

passed tests-py2-pure #67255

00:04:38

passed tests-py3-cext #67256

00:03:40

passed tests-py3-pure #67257

00:03:07