Use pod_target_xcconfig instead of xcconfig in the podspec

[mkval]

Hi there,

First of all, thanks for this awesome library. :)

After adding it to my project via CocoaPods, I noticed some warnings for both Debug and Release configs:

[!] The `MyProject [Debug]` target overrides the `SWIFT_VERSION` build setting defined in `Pods/Target Support Files/Pods-MyProject/Pods-MyProject.debug.xcconfig'. This can lead to problems with the CocoaPods installation
    - Use the `$(inherited)` flag, or
    - Remove the build settings from the target.

[!] The `MyProject [Release]` target overrides the `SWIFT_VERSION` build setting defined in `Pods/Target Support Files/Pods-MyProject/Pods-MyProject.release.xcconfig'. This can lead to problems with the CocoaPods installation
    - Use the `$(inherited)` flag, or
    - Remove the build settings from the target.

Googling led me to CP's Github page that detailed the issue. The advice they gave was to file an issue with the Pod suggesting the usage of pod_target_xcconfig instead of xcconfig in the podspec.

Here's a detailed report made by one of CP's maintainers.

Thanks.

[weakfl]

+1

[melvitax]

Thanks for the heads up. Fixed here: fcdbd2f

[mkval]

Thanks @melvitax