we don't need all the neovim git history to install the latest version (#756)

utils/bin/install-latest-neovim

@@ -1,7 +1,7 @@
 !#/bin/bash
 cd ~
 sudo rm -r neovim
-git clone https://github.com/neovim/neovim
+git clone --branch master --depth 1 https://github.com/neovim/neovim
 cd neovim
 sudo make CMAKE_BUILD_TYPE=Release install
 cd ~