try to bring yadm functionality back into gitsigns (not working)

I think the _on_attach_pre is working, but getting an error when adding
on_attach = function(bufnr) to the gitsigns config..

Started from my MBP at work, syncing so I can pick it up on another
laptop over the weekend if I have time

.config/nvim/lua/plugins.lua

@@ -45,6 +45,7 @@ return packer.startup(function(use)
    })
    use("tpope/vim-obsession")
    use("norcalli/nvim-colorizer.lua")
+   use("seanbreckenridge/gitsigns-yadm") -- bring yadm support back to gitsigns
 
    use("ThePrimeagen/vim-be-good") -- get gud