fix: remove obsolete "version" (#12)

Author: stasadev

docker-compose.memcached.yaml

@@ -8,8 +8,6 @@
 # 4. Optional: adjust the 'command' line below to change CLI flags sent to
 #    memcached.
 
-version: '3.6'
-
 services:
   memcached:
     container_name: ddev-${DDEV_SITENAME}-memcached