AMD GPU information

Only Linux is supported, using the AMDGPU driver.
The library is written using Cython, meaning that Cython and and a
C compiler are needed to build and install from source. Additionally,
libdrm development headers are required.

Precompiled wheels for Python 3.7-3.11 are the default method of
install. This means that you don't need Cython or any other dependencies
to install it normally.

Available functions are (see docstrings for more info):
* detect_gpus - Returns the number of GPUs available
* get_gpu - Returns a GPUInfo object for the device index specified

GPUInfo methods (see docstring for class overview)
* start_utilisation_polling - Starts polling GPU registers for utilisation statistics
* stop_utilisation_polling - Stops the utilisation polling thread
* query_utilisation - Queries utilisation of different GPU parts
* query_max_clocks - Queries max GPU clocks
* query_sclk - Queries shader (core) clock
* query_mclk - Queries memory clock
* query_vram_usage - Queries VRAM usage
* query_gtt_usage - Queries GTT usage
* query_temperature - Queries temperature
* query_load - Queries GPU load
* query_power - Queries power consumption
* query_northbridge_voltage - Queries northbridge voltage
* query_graphics_voltage - Queries graphics voltage

VRAM and GTT sizes are available as an attribute of GPUInfo.

Parts of this package were inspired by [radeontop](https://github.com/clbr/radeontop).