Compile django translations on build time

This makes sure that the .mo files are always up to date in (most?) deployments.
Manual steps that commit these changes can still happen once in a while, like they
currently do.

Fixes #699

Author: rolandgeider

extras/docker/production/Dockerfile

@@ -97,6 +97,8 @@ RUN pip3 install --break-system-packages --user --editable . \
     && mkdir ~/media \
     && mkdir ~/static \
     && mkdir ~/beat \
-    && mkdir ~/db
+    && mkdir ~/db \
+    && cd wger \
+    && django-admin compilemessages
 
 CMD ["/home/wger/entrypoint.sh"]