Adds FFaker::Date.birthday

[professor]

This adds FFaker::Date.birthday

For our use case, we're looking for realistic looking birthdays for employees at a company. It would be weird in our demo/staging environment to have a 3 year old working at a company, not a good look.

In the case of birthday(min_age: 18, max_age: 18), I would interpret this to mean "I want a date for someone who is 18 years old today" -- this means anyone who just turned 18 today back until last year plus a day. So on 9/6/2023 the range would be 9/7/2004 to 9/6/2005 which would be from:9/6/2023 - 19.years + 1.day to: 9/6/2023 - 18.years

I ran this test 10_000 times to verify correctness:

10_000.times do
   assert_random_between(today.prev_year(43).next_day..today.prev_year(42)) { @tester.birthday(min_age: 42, max_age: 42) }
end

Fixes #540

[marocchino]

please add :birthday to assert_methods_are_deterministic

[professor]

Are you ok with me adding TimeCop?

[professor]

@marocchino thanks for all your help with this PR. I appreciate it.

[marocchino]

LGTM

[marocchino]

Are you ok with me adding TimeCop?

Well, Personally, I don't like it. Rails treats it as a legacy that needs to be removed, so I often do the work of removing it.
However, other maintainers may have different thoughts.

[professor]

OK, I believe this PR is ready for merging.

[AlexWayfer]

Are you ok with me adding TimeCop?

What for? For tests? I'm OK if it'd help.

Well, Personally, I don't like it.

Why?

Rails treats it as a legacy that needs to be removed, so I often do the work of removing it.

TimeCop doesn't belong to Rails, what the deal with Rails? It's like "FFaker treats RSpec as a legacy". TimeCop is under active development, as I see, and not even v1 for now:

[professor]

@marocchino anything blocking the merging of this PR?

[marocchino]

I was expecting another maintainer's approval, but it's okay as is.