Fix Nested Map Column Type Parsing Bug

[ehddnr301]

• fixes Reflection fails on complex nested types #269

@xzkostyan

Hello! It's my first pull request.
I want to fix bug for Nested Map columns.

I'm currently using a datahub, and I think modifying the code will make the column types visible

Please feel free to review the changes and provide any feedback or suggestions for improvement.

related datahub issue is datahub-project/datahub#9079

• Additional

Test Table DDL

CREATE TABLE default.deeply_nested_map_table
(
    `id` Int32,
    `deep_map` Map(String, Map(String, Map(String, Map(String, Map(String, Nullable(Int32)))))),
    `other_data` Map(String, Map(String, Map(String, Map(String, Nullable(String)))))
)
ENGINE = MergeTree
ORDER BY id

Before Edit

• TypeError: Map.__init__() missing 1 required positional argument: 'value_type'

After Edit

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
• Ensure PR doesn't contain untouched code reformatting: spaces, etc.
• Run flake8 and fix issues.
• Run pytest no tests failed. See https://clickhouse-sqlalchemy.readthedocs.io/en/latest/development.html.

[ehddnr301]

@xzkostyan

Hello, I just wanted to kindly follow up on my pull request #336.

Please let me know if there's anything I can clarify or improve. Thanks for your time!

[the4thamigo-uk]

Is this likely to ever be merged?