GitHub Actions: Updates to the macOS 10.15 virtual environment

We’ve fully deployed several updates to the macOS 10.15 virtual environment. You can see what changed in the diff here. Highlights include:

    • Xcode 11.2.1 is set by default
    • Added Xcode 11.3
    • Upgraded to Node.js 12.14.0 from 12.13.1
    • Upgraded to Yarn 1.21.1 from 1.19.2
    • Added CMake 3.16.2
    • Upgraded to Visual Studio for Mac 8.3.11.1 from 8.3.10.2
    • Upgraded to Android Emulator 29.3.2 from 29.2.11