Adding Butterfly Access Token

Follow these steps to allow Xcode Swift Package Manager to access our package's binary target:

Quit the Xcode and Keychain Access apps completely (⌘+Q).
Open the Terminal app and run the following command, replacing USERNAME and ACCESS_TOKEN with the Butterfly username and access token provided during onboarding (note: these are not your email and password credentials):
```
security add-internet-password \
   -a USERNAME \
   -w ACCESS_TOKEN \
   -s sdk.butterflynetwork.com \
   -r htps \
   login.keychain-db
```
Ensure that you did not accidentally paste more characters, which can be automatically appended by some note-taking apps. If the Keychain item is created with any mistakes, delete it via the Keychain Access app and re-create it.

You can now continue with adding the package.