Support Nested Map Type (#314)

[aksenof]

• fixes Support nested Map column #314

[aksenof]

@xzkostyan
Hello, Konstantin. It's my first pull request. Just want fix bug for Map columns. We actively use clickhouse-sqlalchemy on my job. And this little fix help us with alembic revision autogenerate without error like in issue #314

[xzkostyan]

Hi.

Please write simple test for this bugfix. See example:

clickhouse-sqlalchemy/tests/sql/test_selectable.py

Line 116 in f261350

def test_nested_type(self):

[coveralls]

coverage: 86.082%. remained the same
when pulling b15776f on aksenof:master
into f261350 on xzkostyan:master.

[aksenof]

Done. Add tests.

[xzkostyan]

Please fix flake8 and tests will re-run.

[aksenof]

flake8 fixed

[coveralls]

coverage: 86.082%. remained the same
when pulling 813e4f3 on aksenof:master
into f261350 on xzkostyan:master.

[aksenof]

@xzkostyan
Please tell me if there is a release clickhouse-sqlalchemy on pypi coming soon? It is possible to release on next month with this bugfix?)

[xzkostyan]

@aksenof version 0.3.2 is released.