Overview of changes in lomiri-gallery-app 3.1.0

  - click/CMakeLists.txt: Install gallery-content.json as
    DATADIR/lomiri-content-hub/peers/lomiri-gallery-app when built in
    non-click mode.
  - Also check if album exists when committing new subtitle.
  - Replace custom TextEditOnClick component by simple TextEdit.
  - Fix: don't discard text changes in TextEditOnClick component.
  - desktop: Fix icons.
  - Move Qt5Test finding to top-level BUILD_TESTING conditional.
  - CMakeLists.txt: Make tests optional.
  - CMakeLists.txt: Add ENABLE_WERROR option.
  - CMake: Fix GNUInstallDirs variable concatenations in CMake.
  - CMake: Stop using qt5_use_modules.
  - Support Exiv2 0.28+.
  - Translation updates (thanks to all contributors on
    hosted.weblate.org).
