#374 asynch, alembic compatibility

[mayty]

• fixes Compatibility issue with asynch==0.3.0 #374
• fixes Broken import due to Alembic removed _reflect_table #368

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.

[mayty]

@xzkostyan Hi, could you take a look at this PR?

[stankudrow]

Hello.

The version v0.2.4 and v0.2.5 are advisable to be excluded: the v0.2.4 might have (if I am not mistaken) and the v0.2.5 has issues with connection management handling logic (an example).

The v0.3.0 seems to be OK except some bugs that are currently under the progress (consider having a look at this PR) and a minor improvement here.

[stankudrow]

This may do:

Suggested change

	'asynch>=0.2.2,<0.4.0',
	'asynch>=0.2.2,!=0.2.4,!=0.2.5,<0.4.0',

https://packaging.python.org/en/latest/specifications/version-specifiers/#id5