properly quote vars

debian/ai-auth-server.service

@@ -9,9 +9,9 @@ Environment=BIND_ADDR=127.0.0.1
 Environment=PORT=1616
 EnvironmentFile=-/etc/default/ai-auth-server
 ExecStart=/usr/bin/ai-auth-server \
-        --config=$CONFIG \
-        --port=$PORT \
-        --addr=$BIND_ADDR \
+        --config=${CONFIG} \
+        --port=${PORT} \
+        --addr=${BIND_ADDR} \
         $DAEMON_ARGS
 Restart=always