Bump git-todo-parser

This fixes a crash in an interactive rebase when there's a merge command in the
rebase-todo file that doesn't have a comment. I don't know under what
circumstances this can happen; git itself doesn't produce these, but it is
theoretically possible for the user to do this manually by doing `git rebase
--edit-todo`, or third-party tools could do it too.

We had one user report a crash because of this, so it seems worth fixing it.

vendor/github.com/stefanhaller/git-todo-parser/todo/parse.go

@@ -110,7 +110,7 @@ func parseLine(line string, commentChar byte) (Todo, error) {
 		}
 		todo.Label = fields[0]
 		fields = fields[1:]
-		if fields[0] == "#" {
+		if len(fields) > 0 && fields[0] == "#" {
 			fields = fields[1:]
 			todo.Msg = strings.Join(fields, " ")
 		}