Need to add Brotli to test_requirements.txt (or somewhere relevent)

[markliu06]

It seems the stock Brotli from Python 3.9 does not work, which the lib need to install from https://github.com/google/brotli in order to make pypoe_exporter to work

Just have a new rig and have to reinstall pypoe yet again. The installation script did not check the version of Brotli or something false postive. And in order to install Brotli via Vcpkg, it need some packages from Build Tools for Visual Studio 2019 https://visualstudio.microsoft.com/downloads/

[markliu06]

altnatively, instead of using Vcpkg version, it seems pip install --upgrade git+https://github.com/google/brotli may work