upgrade this module to fit 3.0

[Hardwell369]

This pull request includes changes to the src/sql_join_2/__init__.py file to improve the handling of SQL inputs and remove unused constants. The most important changes include adding validation for SQL inputs, modifying how SQL strings are read and parsed, and updating the output format.

Improvements to SQL input handling:

• Added validation to ensure sql1 and sql2 are not empty before proceeding with the function execution.
• Modified the way SQL strings are read and checked if they are dictionaries to extract the SQL string properly.

Codebase simplification:

• Removed the LEARNING_ALGORITHMS and FAI_CLUSTERS constants, which were no longer being used in the codebase.

Output format update:

• Changed the output format from writing text to writing JSON, encapsulating the SQL string in a dictionary.