cli/self_update: Fix error when casting to `char*`
cli/self_update: Fix error when casting to `char*`

rust-lang/rustup,inejge/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,nodakai/rustup.rs,nodakai/rustup.rs,rust-lang/rustup,rust-lang/rustup,inejge/rustup.rs,nodakai/rustup.rs,inejge/rustup.rs,inejge/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,inejge/rustup.rs