The Detect Thoughts spell states:
[...] the creature can use its action on its turn to make an Intelligence check contested by your Intelligence check if it succeeds, the spell ends.
This spell is given to the Githzerai race in MToF pg. 96 at 5th level. It is listed as using Wisdom as the spellcasting ability.
When you reach 5th level, you can cast the detect thoughts spell once with this trait [...] Wisdom is your spellcasting ability for these spells.
Does this spell still need the check made by the Githzerai to be Intelligence?
I assume it would.