Fix: Build issue

[EddieLukeAtmey]

Issue

I've followed the steps in Readme.md, pull from develop, run make setup, then open then xcproject file and tried Unit test, Run.

Xcode then compiled with errors (below is just 1 error, there are others similar to it, I guess they comes from the same root cause so I'm not showing it here):

SourceryUtils/Path+Extensions.swift:42: Fatal error: 'try!' expression unexpectedly raised an error: Error Domain=NSCocoaErrorDomain Code=513 "You don’t have permission to save the file “UseCaseProtocol” in the folder “Sourcery”." UserInfo={NSFilePath=/Users/eddie/Library/Caches/Sourcery/UseCaseProtocol, NSUnderlyingError=0x60000100cbd0 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}

Expected

I'm expecting the project to run unit test or just build or run normally

Steps to reproduce

1. Clone from a new mac
2. run make setup
3. open xcodeproj and run

I guess this is something I can fix locally but I don't have any idea. You should include the guide in the readme as well.