Fix some gradle deprecations

[TacoTheDank]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

• Update gradle wrapper 7.3.1 -> 7.3.3
• Update Checkstyle 9.2 -> 9.2.1 (changelog)
• Fixed some well-hidden deprecations (found here)

APK testing

Shouldn't be necessary.

Due diligence

• I read the contribution guidelines.

[triallax]

Update gradle wrapper 7.3.1 -> 7.3.3

Just to clarify, you're upgrading Gradle, not the Gradle wrapper.

[Stypox]

Gradle changes look good according to the documentation, though it's strange that they deprecate things without giving an explanation and an alternative method themselves. The checkstyle update also looks good, as there have only been internal bugfixes in 9.2.1: https://checkstyle.sourceforge.io/releasenotes.html. The app builds just fine, both here and on my pc.

[TacoTheDank]

Thanks :)