fix: broken alembic import with alembic 1.15. Solves issue #368

[thomas-dufour]

• fixes Broken import due to Alembic removed _reflect_table #368

Checklist:

• test locally 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.

[cemsozens]

@xzkostyan Could you take a look at this PR? It will be really helpful to merge this.

[sk-]

@xzkostyan is there any chance this PR could be reviewed and released.

The PR looks good, as the changes are the same that were done in the original alembic's PR.

[thomas-dufour]

@PabloReszczynski thx for the approval. What about merging this PR (I don't know the process in this repo)? Is there anything I need to do?