Fixing errors reported by mypy in search module files - query.py, commands.py and aggregation.py.

[petyaslavova]

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Description of change

Fixing errors reported by mypy.

[Copilot]

Pull Request Overview

This PR fixes mypy type checking errors in the Redis search module by improving type annotations and correcting type inconsistencies across query.py, commands.py, and aggregation.py files.

• Added missing type imports and improved type annotations for better static type checking
• Fixed parameter type definitions to use proper Optional syntax instead of Union with None
• Corrected return type annotations and variable type declarations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
redis/commands/search/query.py	Enhanced type annotations, fixed return types, and improved parameter type definitions
redis/commands/search/commands.py	Replaced Union with None syntax with proper Optional type annotations
redis/commands/search/aggregation.py	Added comprehensive type annotations and fixed method signatures

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