As far as I can tell (and did myself), only the mqqt part needs to change.
The other (old) sensors need to remain under sensor:
For the new mqqt I used:
In your case something like:
mqtt:
#Shelly H&T sensor
sensor:
- name: "Temperatura Studio"
state_topic: "shellies/SensoreHstudio/sensor/temperature"
value_template: "{{ value }}"
unit_of_measurement: "°C"
icon: mdi:thermometer
sensor: #this was missing I think
#Dark Sky weater sensor
- platform: darksky
api_key: !secret darksky_api
language: it
forecast:
- 0
hourly_forecast:
- 0
- 1
monitored_conditions:
- summary
- icon
- temperature
- sunrise_time
- sunset_time
- alerts
- platform: time_date
display_options:
- 'time'
- 'date'
#System monitor sensor
- platform: systemmonitor
resources:
- type: disk_use_percent
arg: /
- type: memory_free
- type: processor_use
- type: last_boot
#Life 360 sensor
- platform: template
sensors:
andrea_phone:
friendly_name: "Batteria Andrea"
unit_of_measurement: '%'
value_template: "{{ state_attr('device_tracker.life360_xxxxx_xxxxx', 'battery') }}"
device_class: battery