Enable Mamba installation in GPU test env

Signed-off-by: Keval Morabia <[email protected]>

Author: kevalmorabia97

tox.ini

@@ -66,7 +66,7 @@ commands_pre =
     pip install git+https://github.com/Dao-AILab/fast-hadamard-transform.git
 
     # Install Mamba model dependencies (takes 8mins!)
-    # pip install --no-build-isolation git+https://github.com/state-spaces/mamba.git
+    pip install --no-build-isolation git+https://github.com/state-spaces/mamba.git
 
     # Install Eagle-3 test dependencies
     pip install tiktoken blobfile sentencepiece