Add type hints to seq()'s increment_by argument

[Neutronlul]

Preamble

The following snippet (adapted from the Recipes docs) results in a pylance error on the non-int increment_by arguments passed to seq() (the float and timedelta())

from datetime import date, timedelta
from model_bakery.recipe import Recipe, seq
from shop.models import Customer
from model_bakery import baker

CustomerRecipe = Recipe(
    Customer,
    age=seq(15, increment_by=3),
    height_ft=seq(5.5, increment_by=0.25),
    # assume today's date is 21/07/2014
    appointment=seq(date(2014, 7, 21), timedelta(days=1)),
    name=seq("Custom num: ", increment_by=2, start=5),
)

customer = baker.make_recipe("shop.CustomerRecipe")
customer.age  # 18
customer.height_ft  # 5.75
customer.appointment  # datetime.date(2014, 7, 22)
customer.name  # 'Custom num: 5'

new_customer = baker.make_recipe("shop.CustomerRecipe")
new_customer.age  # 21
new_customer.height_ft  # 6.0
new_customer.appointment  # datetime.date(2014, 7, 23)
customer.name  # 'Custom num: 7'

There seems to be a fair bit of inconsistency between the code and the docs (and other parts of the code) but I'm going with the assumption that the intended behavior is what's been more recently updated. In this case, that is the behavior of seq(), not its docstring.

In other words, the docs and the docstring make it sound like (at least to me) the value argument should be null for datetime types, but the function body expects them to be passed to value.

Describe the change

Add type hints to seq()'s increment_by argument that align with the function's behavior

PR Checklist

• Change is covered with tests
• CHANGELOG.md is updated if needed

[amureki]

This seems correct to me, thank you for the improvement, @Neutronlul !

One issue is that mypy fails here, but I will try to address it myself.