Log Message:
Update databases/py-cassandra-driver to 3.2.0.

Features
- cqlengine: Warn on sync_schema type mismatch
- cqlengine: Automatically defer fields with the '=' operator
  (and immutable values) in select queries
- cqlengine: support non-equal conditions for LWT
- cqlengine: sync_table should validate the primary key composition
- cqlengine: token-aware routing for mapper statements

Bug Fixes
- Deleting a column in a lightweight transaction raises
  a SyntaxException
- cqlengine: make Token function works with named tables/columns
- comparing models with datetime fields fail #79
- cython date deserializer integer math should be aligned
  with CPython
- db_field is not always respected with UpdateStatement
- Sync_table fails on column.Set with secondary index