Logger returns NameError in non-interactive mode for Python 2

`pytest -s tests/test_noninteractive_mode` shows the following warning:
```Exception ignored in:
Traceback (most recent call last):
File "/Users/ellbosch/Repos/mssql-cli/mssqlcli/mssql_cli.py", line 196, in __del__
File "/Users/ellbosch/Repos/mssql-cli/mssqlcli/sqltoolsclient.py", line 90, in shutdown
File "/Users/ellbosch/Repos/mssql-cli/mssqlcli/jsonrpc/jsonrpcclient.py", line 184, in shutdown
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1378, in info
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1514, in _log
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1524, in handle
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1586, in callHandlers
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 894, in handle
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1126, in emit
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/logging/__init__.py", line 1116, in _open
NameError: name 'open' is not defined
```

Looks like the logger is referenced post-deconstruction.

Start by running pytest -s tests/test_noninteractive_mode, then inspect mssqlcli/mssql_cli.py at __del__, mssqlcli/sqltoolsclient.py at shutdown, and mssqlcli/jsonrpc/jsonrpcclient.py at its logging call. Confirm the teardown path can run during interpreter deconstruction, and consider the issue done when the test no longer emits the NameError warning.

Escrito por el modelo de indexación a partir del texto del issue.