Add mossy cobblestone slab to normal slabs tag

Author: Lucky-56

common/src/main/resources/data/sable/tags/block/normal_slabs.json

@@ -3,6 +3,7 @@
   "values": [
     "minecraft:stone_slab",
     "minecraft:cobblestone_slab",
+    "minecraft:mossy_cobblestone_slab",
     "minecraft:granite_slab",
     "minecraft:diorite_slab",
     "minecraft:andesite_slab",