gmp: update 6.0.0a bottle.
gmp: update 6.0.0a bottle.

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