Skip docs in sbt stage.

[PapyChacal]

Accessorily bump to SBT 1.10.7; I had issues with the current version, and iiuc, this is automatically fetched anyway.

This is according to:

• https://sbt-native-packager.readthedocs.io/en/latest/formats/universal.html#skip-packagedoc-task-on-stage
• stage unnecessarily builds javadoc jar and is slow sbt/sbt-native-packager#651

But I don't see an improvement on my machine.. But I barely notice the docs too. Let's try it out on slower cases first