This project has moved to Planet Minecraft.
Drop wool into a cauldron that has water in it and convert it into dye. This makes dye renewable in a way that doesn't require bone meal.
1.13.* Note: Not all wool colours get converted into dye, to avoid making things like Lapis farmable from sheep. This is not the case in 1.14+, as dye items were added for all colours.
More information about data packs and how to use them can be found on the official Minecraft Wiki.