fix docker compose quotes

docker-compose.dev.yml

@@ -39,11 +39,11 @@ services:
       -  /srv/etherpad/APIKEY.txt:/srv/etherpad/APIKEY.txt
       - theia_usr:/usr/local
     environment:
-      HOST_NAME: "${HOSTNAME}""
+      HOST_NAME: '${HOSTNAME}'
   nginx:
     image: docker.fet.at/nginxdev-fet2020:latest
     ports:
-      - "${PORT}:8080"
+      - '${PORT}:8080'
 volumes:
   ep-mysql:
     driver: local