Redis server: fix warning relarted to memory allocation
See message when Redis starts:
18027:M 12 Nov 2021 12:26:13.622 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.