Sensibo has a built-in feature called “Climate React” which does this exactly. If you do want to use a ST sensor, you might want to look into installing the Sensibo DTH (Sensibo integration) and then using webcore to react to temperature events by turning the Sensibo on/off.
There are also community-made thermostat SmartApps (like: [BETA RELEASE] Multi-feature Programmable Thermostat SmartApp ) which might help eliminate WebCore if you don’t want to go that route.