Add trailing / at the end of spark url

docker-compose-generator/docker-fragments/bitcoin-clightning.yml

@@ -44,7 +44,7 @@ services:
   btcpayserver:
     environment:
       BTCPAY_BTCLIGHTNING: "type=clightning;server=unix://etc/clightning_bitcoin/lightning-rpc"
-      BTCPAY_BTCEXTERNALSPARK: "server=${BTCPAY_PROTOCOL:-https}://${BTCPAY_HOST}${BTCPAY_ROOTPATH:-/}spark/btc;cookiefile=/etc/clightning_bitcoin_spark/.cookie"
+      BTCPAY_BTCEXTERNALSPARK: "server=${BTCPAY_PROTOCOL:-https}://${BTCPAY_HOST}${BTCPAY_ROOTPATH:-/}spark/btc/;cookiefile=/etc/clightning_bitcoin_spark/.cookie"
     volumes:
       - "clightning_bitcoin_datadir:/etc/clightning_bitcoin"
       - "clightning_bitcoin_spark:/etc/clightning_bitcoin_spark"