[d-feet] (10 commits) ...Merge branch 'enable-gitlab-ci' into 'master'

[Thomas Bechtold <toabctl src gnome org>]

Summary of changes:

  12b8b99... Fix coding style errors reported by make check (*)
  520a529... Run tests with same Python version as application (*)
  830fb9b... Detect 'pycodestyle', the new name for 'pep8' (*)
  f5bfec6... Remove bare 'except:' clauses (*)
  9664bdf... Fix a few unused variable/import warnings (*)
  7fa36c5... Ignore W504 line break after binary operator (*)
  45a1146... settings: use r'' strings for regexps (*)
  1e31d1b... flatpak: build with Python 3 (*)
  b97b735... Enable GitLab CI (*)
  e4eac94... Merge branch 'enable-gitlab-ci' into 'master'

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