py2cairo: update 1.15.6 bottle for Linuxbrew.
py2cairo: update 1.15.6 bottle for Linuxbrew.

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