Bump Xcode to 13.0.0 and CocoaPods to 1.11.2

Summary:
Bump the version of Xcode used in internal and external iOS tests, as well as the CocoaPods version used in RNTester (and therefore, the internal CocoaPods offline mirror).

New versions used:
* Xcode 13.0.0
* CocoaPods 1.11.2

See Circle CI Xcode 13.0.0 macOS Container Software manifest: https://circle-macos-docs.s3.amazonaws.com/image-manifest/v6052/index.html
* Xcode 13.0 Build version 13A233
* CocoaPods	1.11.2

Changelog: [Internal]

Reviewed By: fkgozali

Differential Revision: D31253170

fbshipit-source-id: c85f3ee12fa708d9e54fef1200f3124810211d2f