Improve API error handling in networking client

What's Changed

• Make SwiftYNABError public & throw .apiError by @daniel-amoafo in #11

New Contributors

• @daniel-amoafo made their first contribution in #11

Full Changelog: 2.1.0...2.1.1

2.1.0

• Add support for deleting transactions
• Add bank import details

Bug fix

Fix misplacement of closing parenthesis in Package.swift

Async/await

Drops completion blocks in favor of async/await (breaking change)
Bumps minimum supported OS versions to macOS 12, iOS 15, tvOS 15, watchOS 8

1.1.1

• Make payeeId optional in SaveTransaction init

Add support for new budget account creation endpoint

Add support for new budget account creation endpoint announced on Aug 11, 2020.