This release drops support for Python 3.6:
Tortoise ORM now requires a minimum of CPython 3.7

New features:

Model docstrings and #: comments directly preceding Field definitions are now used as docstrings and DDL descriptions.
This is now cleaned and carried as part of the docstring parameter in describe_model(...)
If one doesn't explicitly specify a Field description= or Model Meta.table_description= then we default to the first line as the description.
This is done because a description is submitted to the DB, and needs to be short (depending on DB, 63 chars) in size.
Early Partial Init of models.
We now have an early init of models, which can be useful when needing Models that are not bound to a DB, but otherwise complete.
e.g. Schema generation without needing to be properly set up.
Pydantic serialisation.
We now include native support for automatically building a Pydantic model from Tortoise ORM models.
This will correctly model:
- Data Fields
- Relationships (FK/O2O/M2M)
- Callables
At this stage we only suport serialisation, not deserialisation.
For mode information, please see :ref:contrib_pydantic

Allow usage of F expressions to in annotations. (#301)
Now negative number with limit(...) and offset(...) raise ParamsError. (#306)
Allow usage of Function to queryset.update(). (#308)
Add ability to supply distinct flag to Aggregate (#312)

Bugfixes:

Removed tortoise.aggregation as this was deprecated since 0.14.0
Removed start_transaction as it has been broken since 0.15.0
Removed support for Python 3.6 / PyPy-3.6, as it has been broken since 0.15.0
If you still need Python 3.6 support, you can install tortoise-orm<0.16 as we will still backport critical bugfixes to the 0.15 branch for a while.