changed build settings and removed '.gitkeep'

[devmjun]

When I use pastel through Carthage, I got the following log.

/usr/bin/xcrun xcodebuild -project /Users/minjunju/Desktop/Cart/Carthage/Checkouts/Pastel/Pastel.xcodeproj -scheme Pastel -configuration Release -derivedDataPath /Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1 -sdk iphoneos ONLY_ACTIVE_ARCH=NO CODE_SIGNING_REQUIRED=NO CODE_SIGN_IDENTITY= CARTHAGE=YES archive -archivePath /var/folders/lm/f53m_74j4ns1xhzfykbfrw0m0000gp/T/Pastel SKIP_INSTALL=YES GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=NO CLANG_ENABLE_CODE_COVERAGE=NO STRIP_INSTALLED_PRODUCT=NO (launched in /Users/minjunju/Desktop/Cart/Carthage/Checkouts/Pastel)User defaults from command line:
    IDEArchivePathOverride = /var/folders/lm/f53m_74j4ns1xhzfykbfrw0m0000gp/T/Pastel
    IDEDerivedDataPathOverride = /Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1

Build settings from command line:
    CARTHAGE = YES
    CLANG_ENABLE_CODE_COVERAGE = NO
    CODE_SIGN_IDENTITY = 
    CODE_SIGNING_REQUIRED = NO
    GCC_INSTRUMENT_PROGRAM_FLOW_ARCS = NO
    ONLY_ACTIVE_ARCH = NO
    SDKROOT = iphoneos12.0
    SKIP_INSTALL = YES
    STRIP_INSTALLED_PRODUCT = NO

note: Using new build system
note: Planning build
note: Constructing build description
Build system information
warning: The use of Swift 3 @objc inference in Swift 4 mode is deprecated. Please address deprecated @objc inference warnings, test your code with “Use of deprecated Swift 3 @objc inference” logging enabled, and then disable inference by changing the "Swift 3 @objc Inference" build setting to "Default" for the "Pastel" target. (in target 'Pastel')

Build system information
warning: The use of Swift 3 @objc inference in Swift 4 mode is deprecated. Please address deprecated @objc inference warnings, test your code with “Use of deprecated Swift 3 @objc inference” logging enabled, and then disable inference by changing the "Swift 3 @objc Inference" build setting to "Default" for the "Pastel" target. (in target 'Pastel')

Build system information
warning: duplicate output file '/Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1/Build/Intermediates.noindex/ArchiveIntermediates/Pastel/IntermediateBuildFilesPath/UninstalledProducts/iphoneos/Pastel.framework/.gitkeep' on task: CpResource /Users/minjunju/Desktop/Cart/Carthage/Checkouts/Pastel/Pastel/Classes/.gitkeep /Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1/Build/Intermediates.noindex/ArchiveIntermediates/Pastel/IntermediateBuildFilesPath/UninstalledProducts/iphoneos/Pastel.framework/.gitkeep (in target 'Pastel')

Build system information
error: Multiple commands produce '/Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1/Build/Intermediates.noindex/ArchiveIntermediates/Pastel/IntermediateBuildFilesPath/UninstalledProducts/iphoneos/Pastel.framework/.gitkeep':
1) Target 'Pastel' (project 'Pastel') has copy command from '/Users/minjunju/Desktop/Cart/Carthage/Checkouts/Pastel/Pastel/Assets/.gitkeep' to '/Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1/Build/Intermediates.noindex/ArchiveIntermediates/Pastel/IntermediateBuildFilesPath/UninstalledProducts/iphoneos/Pastel.framework/.gitkeep'
2) Target 'Pastel' (project 'Pastel') has copy command from '/Users/minjunju/Desktop/Cart/Carthage/Checkouts/Pastel/Pastel/Classes/.gitkeep' to '/Users/minjunju/Library/Caches/org.carthage.CarthageKit/DerivedData/10.0_10A255/Pastel/0.5.1/Build/Intermediates.noindex/ArchiveIntermediates/Pastel/IntermediateBuildFilesPath/UninstalledProducts/iphoneos/Pastel.framework/.gitkeep'

** ARCHIVE FAILED **`

I think a problem because of'.gitkeep' exists. so I had deleted the .gitkeep in the Classes folder.

In addition, I don't know a reason that whether you intend to set swift 3 @objc inference to 'on'. I have changed it to default because of proposals

Please review myPR.
thank you

[cruisediary]

🏄 link added stackoverflow

[cruisediary]

@devmjun thank you for your first PR on Pastel
I checked your reporting and worked fine. 🎉
after I read SE-0160 and related documents, I will merge this PR thank you 😄

[cruisediary]

@devmjun thank you :)