Merge branch 'develop' into hotfix-3.2.3

Author: syre

docker/Dockerfile

@@ -85,7 +85,7 @@ RUN set -ex \
 # Install requirements
 COPY backend/requirements.txt /code/backend/requirements.txt
 COPY backend/requirements-test.txt /code/backend/requirements-test.txt
-RUN pip3 install -r backend/requirements-test.txt
+RUN pip3 install --no-cache-dir -r backend/requirements-test.txt
 
 
 # Copy and install backend code.