Striders are not part of the "Two by Two" advancement challenge

The bug

Recently added mob, Strider, is not part of the "Two by Two" advancement.

To reproduce

1. Find 2 Strider(s) in the Nether, or spawn them with eggs in creative mode.
2. Breed them warped fungus.
3. The baby is born! 
     - Is part of the "The Parrots and the Bats" advancement.
     - It's not part of the "Two by Two" advancement challenge