[d-feet] (6 commits) ...Merge branch 'fix-bugs-in-mr-7' into 'master'

[Thomas Bechtold <toabctl src gnome org>]

Summary of changes:

  539bcc1... settings: fix regexp syntax, add a test (*)
  6bbcc29... ci: correctly build to use python3 (*)
  767f82d... flatpak: install pycodestyle during build (*)
  72a62e5... ci: run tests in Flatpak build (*)
  ee9c5aa... ci: build Flatpak in .app, not app (*)
  b512c7f... Merge branch 'fix-bugs-in-mr-7' into 'master'

(*) This commit already existed in another branch; no separate mail sent