Use case tests improvement

Now the user can see which unexpeted actions have been received.

Dark/Light mode for snapshot tests

Merge pull request #5 from SwiftRex/darkModeSupport

Adds support for dark / light mode snapshots

Update SwiftRex

Update to SwiftRex 0.8.4

DSL Tests <3 resultBuilder

Fixed the diagnostic message when expected state mutation doesn't happen.
Make it work on Swift 5.3 (without resultBuilders)
Allow resultBuilders inside resultBuilders, so groups of steps can be extracted to functions.

DSL Tests <3 resultBuilder

Tests can be written using DSL style, similar to SwiftUI views composition, thanks to the newly added resultBuilder!
Check the README for some examples!
Extensions for Combine async tests are also improved and documented.

Better Step definitions

To overcome the fact that enum cases can't be generic, now there's a struct definition for SendStep and ReceiveStep.

Update all dependencies

Update SwiftRex and all dependencies

Building again on Xcode 11

v0.1.6

Fix Xcode 11 build

Always target latest stable SwiftRex release

v0.1.5

Make master in sync with latest SwiftRex release

Switching back to the official repository

v0.1.4

Update Package.swift