Without this dependency, kfilmetadata will show below build error in Arch Linux(System Qt is 5.14 now).
[ 54%] Linking CXX executable ../bin/popplerextractortest
/usr/bin/ld: /usr/lib/libpoppler-qt5.so: undefined reference to `qt_version_tag@Qt_5.14'
/usr/bin/ld: /usr/lib/libpoppler-qt5.so: undefined reference to `QLinearGradient::~QLinearGradient()@Qt_5'