How to make Unbreakable tools in Minecraft 17w48a (1.13 minecraft snapshot)?

If I remember correctly, the nbt data is now part of the (item) argument. You have to write your command like this:

/give @s minecraft:(put weapon here){Unbreakable:1} 1

put in the weapon without ( and )

In order to do this command in the 1.13 snapshots [17w48a or any other snapshot relating to 1.13] is to execute your command like this, with the NBT next to the item name, rather than after the damage.

/give @p diamond_pickaxe{Unbreakable:1b} 1

If you want to hide the "Unbreakable" flag on the pickaxe when you hover your cursor over it in the inventory, simply do this

/give @p diamond_pickaxe{Unbreakable:1b,HideFlags:4} 1

You can, if you want, replace @p with @s.

You can go here for more information: Tutorials/Command NBT tags - Official Minecraft Wiki