Merge remote-tracking branch 'remotes/origin/branches/workflow_update…

…2_REBASED'

Update of io.github.JakubMelka.Pdf4qt.appdata.xml

Release of version 1.3.7

Issue #96: PDF4QT crashes when I open PDF

Release of version 1.3.4

Flatpak test

Directory fix

Fix build system for plugins

New 128x128 application icons for linux

Fix filenames for flatpak again