Release v0.12.20

• v0.12.20
  • Started the SDK beta program. A beta version of the SDK is now available.
    • See the Github info here: https://branch.app.link/5HMUVrQeYy
  • Updated the build script.
  • Merge pull request #517 from brianmichel/bsm/call-javascript-from-main-thread.
  • Fixed and re-applied patches from v0.12.18. These are:
    • Updated share channel names for some older iOS app versions.
    • Updated how the SFSafariViewController window is handled when finding a strong match.
      • The keyWindow and firstResponder will no longer lose focus at app start up (#484, AIS-122).
      • Branch now plays nicely with the Facebook login controller (AIS-122).
    • Improved handling of queued link opens. (#491, #503, AIS-128)
    • Made the preference helper more robust to prevent crashes (#514)
    • Updated nullability of callback parameters for Swift (#509, #507, AIS-149).
    • Fixed some nil reference errors found by static analysis.
    • Fixed a small memory leak.