Fix issues with case sensitive email addresses sent by some SSO providers

[Convly]

What does it do?

Use a case-insensitive lookup for admin users in the findOneByEmail method of the user service.

Why is it needed?

See #16982

How to test it?

• Manually by executing yarn strapi console and then making a manual query to the admin user service.
• Or just by running the unit tests

Related issue(s)/PR(s)

fix #16982

[innerdvations]

Was this working in 4.14 and broken in 4.15? If not, let's target main to avoid potentially introducing something new.

[Convly]

I figured this could be an easy fix to have in the next release but if we want to be extra cautious I can target another version

[innerdvations]

LGTM!

Just to be sure, I also confirmed that the unique check on account creation is case insensitive (that is, it shouldn't be possible to have multiple accounts with different casing) so this should be safe.

The base branch was changed.

[innerdvations]

I figured this could be an easy fix to have in the next release but if we want to be extra cautious I can target another version

Yeah, it seems very simple and totally safe to me, but those are always the ones that always seem to end up breaking something unexpected 😆

[derrickmehaffy]

building experimental: https://github.com/strapi/strapi/actions/runs/7090551315