[BUG] friendly_name detection rule

[fofyga]

Hi. You detect friendly_name as
friendly_name: '{{ topic_var.split(''/'')[1] | regex_replace("[^A-Za-z0-9_/./-]", "") }}'
In cases when users use custom zigbee2mqtt topic it doest work. For example i use
"/devices/zigbee2mqtt/0x54ef441000c39a1a", in that case i need to get [3] index.

I mean it makes sense to take the last element of the array, because friendly_name always places after last slash '/' symbol.