ci: update dockerfiles

oragono got renamed, and distros have been updated in the last decade

docker/test/fedora/Dockerfile

@@ -1,9 +1,9 @@
 # This Dockerfile creates a docker image suitable to run biboumi’s build and
 # tests.  For example, it can be used on with gitlab-ci.
 
-FROM docker.io/fedora:32
+FROM fedora:latest
 
-ENV LC_ALL C.UTF-8
+ENV LC_ALL=C.UTF-8
 
 RUN dnf --refresh install -y \
 git \
@@ -35,7 +35,7 @@ rpmdevtools \
 && dnf clean all
 
 # Install slixmpp, for e2e tests
-RUN git clone https://lab.louiz.org/poezio/slixmpp && pip3 install pyasn1 && cd slixmpp && python3 setup.py build && python3 setup.py install
+RUN pip3 install --break-system-packages slixmpp
 
 # Install oragono, for e2e tests
 RUN wget "https://github.com/oragono/oragono/releases/download/v2.0.0/oragono-2.0.0-linux-x64.tar.gz" && tar xvf oragono-2.0.0-linux-x64.tar.gz && cp oragono-2.0.0-linux-x64/oragono /usr/local/bin