The go.mod imports all SDK/clients when it shouldn't have to

[SaimonWoidig]

Hello. 👋
First of all - this is a great package and it is exactly what I was looking for! Thank you!
Ok to the point - I think that it should be able to split the singular package into core and into multiple services/.... Each of the service package would then import the necessary SDKs and clients and implement the actual sending logic.
This would be a notable change and would possibly break things, so maybe a v2 would be in order. But it should cut down the time to go get the package, since the user would import only what he needs (given by the service). It would also possibly affect the CI/CD workflow - I don't know the exact settings and tooling you are using (I've seen Codecov).
Again thanks and feel free to correct me if I am mistaken.