fix: correct dict comprehension syntax in save_pretrained to prevent ValueError

[ajayraj30002]

What does this PR do?

Fixes #47333

There is a small syntax error in modeling_utils.py that crashes the save_pretrained process for models with offloaded modules.

Currently, weight_map.update() is being passed a generator yielding single-key dictionaries, which throws a ValueError because update() expects a sequence of 2-item tuples.

Before:
weight_map.update({k: os.path.basename(shard_file)} for k in shard_state_dict.keys())

After (moved the closing brace to make it a standard dict comprehension):
weight_map.update({k: os.path.basename(shard_file) for k in shard_state_dict.keys()})

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@Cyrilvallez @SunMarc (Tagging you as you were mentioned in the original issue!)

[github-actions]

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[Rocketknight1]

#47336 was open already with this fix + the actual fix!