1.22.3 (CocoaPods)

Changes

• Up until this release, the level podspec lived in https://github.com/firebase/leveldb-library-podspec and pointed to the https://github.com/google/leveldb.git repo. Now, it lives in this repo and points to this repo's sources.
• Fixes warnings for CocoaPods users that were previously fixed for SwiftPM users in #4.