Bump metadata version from 2 to 12
Bump metadata version from 2 to 12

The format of the installed toolchains has changed.

The big jump is to leave room for multirust.sh to leave room
for multirust.sh to make its own diverging versions.

polonez/rustup.rs,Boddlnagg/rustup.rs,theindigamer/rustup.rs,nodakai/rustup.rs,inejge/rustup.rs,inejge/rustup.rs,Boddlnagg/rustup.rs,polonez/rustup.rs,inejge/rustup.rs,polonez/rustup.rs,inejge/rustup.rs,rust-lang/rustup,rust-lang/rustup,Boddlnagg/rustup.rs,nodakai/rustup.rs,inejge/rustup.rs,nodakai/rustup.rs,theindigamer/rustup.rs,polonez/rustup.rs,nodakai/rustup.rs,nodakai/rustup.rs,Boddlnagg/rustup.rs,theindigamer/rustup.rs,rust-lang/rustup,theindigamer/rustup.rs,rust-lang/rustup,Boddlnagg/rustup.rs,theindigamer/rustup.rs,rust-lang/rustup,polonez/rustup.rs