remove VALID_ARCHS (deprecated since XCode 12 i think)

[eliburke]

I was unable to run in an x86_64 simulator until removing this build setting.

https://developer.apple.com/documentation/xcode-release-notes/xcode-12-release-notes

The Build Settings editor no longer includes the Valid Architectures build setting (VALID_ARCHS), and its use is discouraged. Instead, there is a new Excluded Architectures build setting (EXCLUDED_ARCHS). If a project includes VALID_ARCHS, the setting is displayed in the User-Defined section of the Build Settings editor. (15145028)

[paulocoutinhox]

merge merge merge +1