Remove Cargo authors line

[notmandatory]

          In a future PR I want to remove this line and replace it with:

homepage = "https://bitcoindevkit.org"
repository = "https://github.com/bitcoindevkit/bdk"

Originally posted by @notmandatory in #402 (comment)

[notmandatory]

@artfuldev since we have alot of new devs I want to remove the authors line from the Cargo.toml and other parts of the projects to replace with "Bitcoin Dev Kit Developers". Since it's only you and I as "authors" now I want to confirm, do you have any concerns making this change?

[artfuldev]

Please go ahead, it's amazing to have all these new devs! 🙂

[thunderbiscuit]

Merged with #425!