py3cairo: Help py3cairo to find python-config.py for Linuxbrew
py3cairo: Help py3cairo to find python-config.py for Linuxbrew

Linuxbrew/homebrew-core,rwhogg/homebrew-core,rwhogg/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,LinuxbrewTestBot/homebrew-core,maxim-belkin/homebrew-core,maxim-belkin/homebrew-core