Firebase Admin .NET SDK v2.3.0

Miscellaneous

• [chore] Release 2.3.0 Take 2 (#321)
• Revert "[chore] Release 2.3.0 (#319)" (#320)
• [chore] Release 2.3.0 (#319)
• feat (fcm): Add additional Android Notification Parameters (#317)
• chore: Build .net framework targets on linux (#318)
• Update nightly.yml
• Update run_integration_tests.sh
• Update nightly.yml
• Update run_integration_tests.sh
• chore: Changing back to ubuntu-latest
• Rename run_integration_tests.ps1 to run_integration_tests.sh
• chore: switching to windows-latest
• chore: Install .NET Core SDKs explicitly
• Setup .NET Core
• Setup .NET Core on all platforms
• Switching nightly script back to windows-2019
• Changing nightly builds to use ubuntu-latest
• Set .NET core version in Nightly builds
• Revert "Add delayed response message for holidays (#311)" (#312)
• Add delayed response message for holidays (#311)
• chore: Add nightly build workflow (#305)