fix type annotation for ALL_ATTENTION_FUNCTIONS
Author: WineChord
Pull request: yes

Corrects the type annotation to match actual usage. The variable was typed as Dict[str, Dict[str, Callable]] but is actually used as Dict[str, Callable] where keys are attention mechanism names and values are the corresponding attention functions directly. This change makes the type annotation consistent with how the dictionary is used in the codebase.

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