build: upgrade gradle 6.5 -> 8.2.1

[keturn]

Relates to MovingBlocks/Terasology#5109
Relates to MovingBlocks/Terasology#4653

Contains

• Updating gradle from 6.5 -> 8.2.1
• Updating gradle's files for which became invalid

How to test

• run gradlew build -> do we build JNBullet this way?
• we could further test it in combination with Terasology (groovyw lib get JNBullet && gradlew jar game)

Remarks

Java 20 is not yet supported, see gradle/gradle#23488.

Closes #13

[jdrueckert]

@pollend I updated this and I'm not sure whether the commit that updates swig-src files should be in here or whether we're missing something in our gitignore? The files just auto-updated when I ran ./gradlew tasks 👀

[pollend]

I thought there was some scripts to generate the updated classes.i ? if this works with the current version of Terasology I can't see why this won't hurt. I think for the lib sources it's coming from artifactory, did you try building it from cpp source?

[soloturn]

gradle-8.2.1 got released, better use that one?

[jdrueckert]

did you try building it from cpp source?

@pollend nope didn't... should I try that or do you think building in the Terasology context (by including it in the libs dir) would work and be sufficient?