Update changelog

This is mainly to give me a version number I can use in other packages'
dependencies.

Signed-off-by: Simon McVittie <smcv@collabora.com>
6 jobs for master in 7 minutes and 56 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
manual build:arch #40338
allowed to fail manual
passed build:asan #40334

00:03:15

passed build:bionic #40337

00:07:49

passed build:buster #40336

00:07:40

passed build:stretch #40335

00:07:56

passed build:ubsan #40333

00:03:33