fix ssl redirects when using internal openproject url in hocuspocus (#144)

docker-compose.yml

@@ -126,6 +126,7 @@ services:
     environment:
       SECRET: ${COLLABORATIVE_SERVER_SECRET:-OVERRIDE_ME_PLEASE}
       OPENPROJECT_URL: "${OPENPROJECT_URL:-http://web:8080}"
+      OPENPROJECT_HTTPS: "${OPENPROJECT_HTTPS:-true}"
     networks:
       - backend
       - frontend