Added our Python venv to the PATH variable

Now users can run "manage.py" without specifying the full path.

Dockerfile

@@ -85,7 +85,7 @@ RUN mkdir -p static /opt/unit/state/ /opt/unit/tmp/ \
           --config-file /opt/netbox/mkdocs.yml --site-dir /opt/netbox/netbox/project-static/docs/ \
       && SECRET_KEY="dummy" /opt/netbox/venv/bin/python /opt/netbox/netbox/manage.py collectstatic --no-input
 
-ENV LANG=C.UTF-8
+ENV LANG=C.UTF-8 PATH=/opt/netbox/venv/bin:$PATH
 ENTRYPOINT [ "/usr/bin/tini", "--" ]
 
 CMD [ "/opt/netbox/docker-entrypoint.sh", "/opt/netbox/launch-netbox.sh" ]