[Sqlalchemy-tickets] Issue #4339: DeprecationWarnings on Python 3.7 (zzzeek/sqlalchemy)

[Karthikeyan <iss...@bi...>]

New issue 4339: DeprecationWarnings on Python 3.7
https://bitbucket.org/zzzeek/sqlalchemy/issues/4339/deprecationwarnings-on-python-37

Karthikeyan:

Trying to use the project on CPython master generates the below warnings. I think these were added in Python 3.7 and CPython master is the development branch for 3.8 release. Hence this might cause incompatibility with SQLAlchemy in the future. I don't know if there are other places where this causes issue. I came across this while using records which SQLAlchemy under the hood.

```
#!python

/home/karthi/records-venv/lib/python3.8/site-packages/sqlalchemy/sql/base.py:49: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
  class _DialectArgView(collections.MutableMapping):

/home/karthi/records-venv/lib/python3.8/site-packages/sqlalchemy/engine/result.py:182: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
  from collections import Sequence
```

CPython commit that added the warning : https://github.com/python/cpython/commit/c66f9f8d3909f588c251957d499599a1680e2320

Relevant files : 

https://bitbucket.org/zzzeek/sqlalchemy/src/0e1ee3f5ce6af9b20dab6593f4a34f3bf1871f84/lib/sqlalchemy/sql/base.py#lines-49

https://bitbucket.org/zzzeek/sqlalchemy/src/0e1ee3f5ce6af9b20dab6593f4a34f3bf1871f84/lib/sqlalchemy/engine/result.py#lines-182

Thanks much for SQLAlchemy :)