Pin Ray version to 2.40.0 (#13490)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

Author: WoosukKwon

requirements-cuda.txt

@@ -2,7 +2,7 @@
 -r requirements-common.txt
 
 # Dependencies for NVIDIA GPUs
-ray[adag] == 2.41.0 # Required for pipeline parallelism in V1.
+ray[adag] == 2.40.0 # Required for pipeline parallelism in V1.
 torch == 2.5.1
 torchaudio==2.5.1
 # These must be updated alongside torch