Update dependencies to brevo

[Benjamin-K]

Sendinblue is now Brevo. So we need to update our dependencies to use the new Brevo sdk and maybe rename the package.

[mgrundkoetter]

Any updates here?

[Benjamin-K]

Hi @mgrundkoetter,
As the old SDK is still working we didn't set a high priority on this. Maybe we will find some time between the years. Otherwise, feel free to create a PR.