Fix deprecation of Bundle.getSerializable(String) by using BundleCompat

[TobiGr]

What is it?

• [ ] Bugfix (user facing)
• [ ] Feature (user facing) ⚠️ Your PR must target the refactor branch
• [x] Codebase improvement (dev facing)
• [ ] Meta improvement to the project (dev facing)

Description of the changes in your PR

This fixes the following warning during compilation:

file:app/src/main/java/org/schabi/newpipe/about/LicenseFragment.kt:36:55 'fun getSerializable(p0: String?): Serializable?' is deprecated. Deprecated in Java.

APK testing

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Due diligence

• [x] I read the contribution guidelines.