Remove duplicated extras["retrieval"]

[n1t0]

The extras["retrieval"] is defined a few lines above as:

transformers/setup.py

Lines 217 to 222 in 28b2601

	if os.name == "nt": # windows
	extras["retrieval"] = deps_list("datasets") # faiss is not supported on windows
	extras["flax"] = [] # jax is not supported on windows
	else:
	extras["retrieval"] = deps_list("faiss-cpu", "datasets")
	extras["flax"] = deps_list("jax", "jaxlib", "flax")

and then it seems to be overridden just below, probably linking to faiss-cpu being included even on windows.

This PR removes the second assignment.

cc @LysandreJik @sgugger @stas00

[sgugger]

Thanks for fixing!

[LysandreJik]

LGTM, thanks @n1t0!