dotdrop: Use `git diff` for cross-platform colored diffs
dotdrop: Use `git diff` for cross-platform colored diffs

The macOS `diff` command doesn't support the `--color` option, but `git
diff` does, and with the `--no-index` it can be used to compute diffs
between files on the filesystem (rather than diffing versions of files
within a repository).

razzolini/dotfiles,razzolini/dotfiles,razzolini/dotfiles