Log Message:
databases/py-peewee: Update to 3.4.0.

Backwards-incompatible changes

- The regexp() operation is now case-sensitive for MySQL and Postgres.
  To perform case-insensitive regexp operations, use iregexp().
- The SQLite BareField() field-type now supports all column
  constraints except specifying the data-type. Previously it silently
  ignored any column constraints.
- LIMIT and OFFSET parameters are now treated as parameterized values
  instead of literals.
- The schema parameter for SQLite database introspection methods is no
  longer ignored by default. The schema corresponds to the name given
  to an attached database.
- ArrayField now accepts a new parameter field_kwargs, which is used
  to pass information to the array field's field_class initializer.

New features and other changes

- SQLite backup interface supports specifying page-counts and a
  user-defined progress handler.
- GIL is released when doing backups or during SQLite busy timeouts
  (when using the peewee SQLite busy-handler).
- Add NATURAL join-type to the JOIN helper.
- Improved identifier quoting to allow specifying distinct
  open/close-quote characters. Enables adding support for MSSQL, for
  instance, which uses square brackets, e.g. [table].[column].
- Unify timeout interfaces for SQLite databases (use seconds
  everywhere rather than mixing seconds and milliseconds, which was
  confusing).
- Added attach() and detach() methods to SQLite database, making it
  possible to attach additional databases (e.g. an in-memory cache
  db).