[BUG]: Llama3.1-8B to fix

[Monstertail]

Description of the bug

Two errors:

1. the rope is not correct. refer to here to fix it;
2. the request pool is too small. For speculative decoding with llama3.1-8B, when the tree size is larger than 128, it has an error:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/data/jinweiy/deft/project_deft/DeFT/deft/tree_decoding/branch_controller.py", line 23, in apply_branching
return self.branching_function(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/data/jinweiy/deft/project_deft/DeFT/deft/tree_decoding/generation/branch_func_example.py", line 403, in example_branch_Func4_SpeculativeDecoding
model.tree.branch(model.tree.root, token_tree_size)
File "/data/jinweiy/deft/project_deft/DeFT/deft/tree_decoding/tree_cache.py", line 361, in branch
assert new_req is not None
^^^^^^^^^^^^^^^^^^^
AssertionError

Steps To Reproduce

run speculative decoding with llama3.1-8B and set the tree size>=128.

Additional Information

No response