LXC images with stable apkg

See ci/lxc/README.md

ci/lxc/opensuse-15.4/Dockerfile

 FROM registry.nic.cz/labs/lxc-gitlab-runner/opensuse-15.4
 ENV LC_ALL=C.UTF-8
+ENV PATH="~/.local/bin:${PATH}"
 
 WORKDIR /root
 CMD ["/bin/bash"]
+SHELL ["/bin/bash", "-c"]
 
 
 # packaging deps
-RUN zypper install -y curl git rpm-build python3-pip
+RUN zypper install -y curl git rpm-build python3-pip python3-virtualenv
 # basic deps
 RUN zypper install -y python3-beautifulsoup4 python3-setuptools python3-Jinja2 python3-click python3-distro python3-blessings python3-requests python3-toml python3-cached-property
 # systemd
 RUN zypper install -y systemd
 # install stable apkg from PyPI
-RUN python3 -m pip install apkg
+RUN echo 'PATH="~/.local/bin:${PATH}"' >> ~/.bashrc
+RUN python3 -m pip install pipx
+RUN pipx install apkg
 RUN apkg --version