Return cursor to previous cursor position (#101)

`GoGet` and `GoMod` opens up a new split and move the cursor there.
If the cursor isn't moved back to the *.go buffer, `utils.restart`
will try to spawn gopls in the terminal split, which results in
gopls failed to restart properly.

lua/go/runner.lua

@@ -91,6 +91,9 @@ local run = function(cmd, opts)
     end,
   })
 
+  -- Return to previous cursor position
+  api.nvim_command("wincmd p")
+
   -- uv.read_start(stdout, vim.schedule_wrap(on_stdout))
 
   uv.read_start(stderr, function(err, data)