Allow multiple template paths

[a-babarytskyi]

Updating type annotation, since jinja accepts list of paths and will look for potential templates in all of them. Especially helpfull if you have a lot of templates that rely on similar base higher in hierarchy.

No other changes required, tested locally.

[sabuhish]

Hey @a-babarytskyi!

Thanks looking into it. Okay jinja can accept list of paths, but is fastapi-mail supports this? Also, naming convention wont be correct in this case for template folder, s letter should have at the end. Another question raises, do we have tests for this case?