gather temperatures from ThermalSubsystem instead of deprecated Thermal

[fschlich]

The Thermal schema was deprecated in release 2020.4:

This schema has been deprecated and use in new implementations is discouraged except to retain compatibility with existing products. This schema has been deprecated in favor of the ThermalSubsystem schema. (https://www.dmtf.org/sites/default/files/standards/documents/DSP2046_2024.1.pdf page 921)

gofish apparently added support for ThermalMetrics in April, released as part of v0.16.0 with further bugfixes in v0.16.1

I'm currently facing an issue where Dell PowerEdge servers with external enclosure PowerVault MD2412 would report duplicate MemberId for several temperature sensors and fans when using the /redfish/v1/Chassis/Enclosure.External.0-1:NonRAID.Slot.7-1/Thermal endpoint. Dell Support have accepted the issue, but point out that Thermal is deprecated and ThermalSubsystem, or specifically /redfish/v1/Chassis/Enclosure.External.0-1:NonRAID.Slot.7-1/ThermalSubsystem/ThermalMetrics yields the same data with unique IDs.

Please consider switching redfish_exporter to query the non-deprecated ThermalMetrics schema.