From Fedora Project Wiki
Plugins
OMEMO
OMEMO dependencies
install OMEMO dependencies via pip
sudo dnf install -y python3-devel
sudo pip3 install python-axolotl
install OMEMO dependencies via corp philfry/gajim
sudo dnf copr enable -y philfry/gajim
sudo dnf install -y python-axolotl
- or
sudo dnf install -y python3-axolotl