@n3em3o Did you installed the grove.py on the raspberry pi? if not please do that first.
with the single command below, we can install/update all dependencies and latest grove.py.
curl -sL https://github.com/Seeed-Studio/grove.py/raw/master/install.sh | sudo bash -s -
and try again! please not that, the Seeed Temperature_Sensor_V1.2 is Analog one so you should temperature sensor to port A0 of the Base Hat. like image below.
More information:
Grove Base Hat for Raspberry Pi (Grove Base Hat for Raspberry Pi | Seeed Studio Wiki)
Grove - Temperature Sensor V1.2(Grove - Temperature Sensor V1.2 | Seeed Studio Wiki)