CI: image tweaks

qt5_docs can go back to debian unstable

clazy one still needs fedora 31, on fedora 32 clazy crashes, they are
investigating it
11 jobs for master in 7 minutes and 25 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #3514398
build

00:04:44

passed #3514403
build_android

00:00:54

passed #3514399
build_clang_libcpp

00:04:33

passed #3514402
build_clazy

00:02:05

passed #3514401
build_mingw64_fedora

00:03:04

passed #3514400
build_ubuntu_16_04

00:01:26

passed #3514397
clang_format

00:01:12

 
  Document
passed #3514405
cpp_docs

00:02:08

passed #3514406
glib_docs

00:02:21

passed #3514404
qt5_docs

00:02:14

 
  Publish
passed #3514407
trigger_pages

00:00:18