Bump Lighthouse down to v6 before mainnet rollout of charon 1.3

Author: OisinKyne

docker-compose.yml

@@ -46,7 +46,7 @@ services:
   #      |___/
 
   lighthouse:
-    image: sigp/lighthouse:${LIGHTHOUSE_VERSION:-v7.0.0-beta.5}
+    image: sigp/lighthouse:${LIGHTHOUSE_VERSION:-v6.0.1}
     ports:
       - ${LIGHTHOUSE_PORT_P2P:-9000}:9000/tcp # P2P TCP
       - ${LIGHTHOUSE_PORT_P2P:-9000}:9000/udp # P2P UDP