v1.2.1 5GMS Application

What's Changed

• UI changes for portrait mode by @dsilhavy in #46 #47
• Upgrade compileSdk and targetSdk, upgrade Gradle version and Github action update by @dsilhavy in #47
• Adjustments in the readme for DVB-I Player by @jordijoangimenez in #42

Full Changelog: rt-5gms-application-v1.2.0...rt-5gms-application-v1.2.1