Fix Cloud SQL example (MySQL) (#2309)
Fix Cloud SQL example (MySQL) (#2309)

The sample has the wrong format for `unix_socket` inside the query parameter in sqlalchemy.create_engine.

Doing:

    '/cloudsql/{}/'.format(cloud_sql_connection_name)

takes the path as a directory so the ending slash needs to be removed:

    '/cloudsql/{}'.format(cloud_sql_connection_name)
GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples