[Update] Update the License for the Pod "AppsFlyer-SDK". The license is ...

The license for the Pod "AppsFlyer-SDK" is wrong. It was listed as MIT but the SDK is commercial, as you can see here [1] and here [2].

Also, the LICENSE file is listed in the podspec but missing in the repository, thus it's generating a warning when "pod update" or "pod install":

> [!] Unable to read the license file `*****/LICENSE` for the spec `AppsFlyer-SDK (2.5.3.10)`

[1] http://www.appsflyer.com/terms-of-use/
[2] http://support.appsflyer.com/attachments/token/tGvAWXpasuGAz9mLuMHQhn0Z0/?name=AF-iOS-Integration-Guide-v2.5.3.10-New-API.pdf