recover support for older Julia versions

[lmiq]

@carstenbauer

I started updating packages that depend on ChunkSplitters, and noted that we are artificially dropping support for older Julia versions than 1.10. Thus, if we are to suggest people to upgrade, everyone will be forced to drop their support as well.

This is quite inconvenient now, particularly since 1.6 is (still) the LTS, and many people are using 1.9. I feel that suggesting PRs to packages that depend on ChunkSplitters while forcing them to drop support of older Julia versions just for it is not very nice.

The only test that fails in 1.6 is the allocation test with size set, but it does not fail in 1.9 anymore.

[carstenbauer]

Alright, let's keep/recover 1.6 support. However, I'd drop it once 1.10 is officially declared the new LTS.

[carstenbauer]

This needs a entry in CHANGELOG.md (for version 3.1).

Regarding the broken test, can you add a @test_broken conditioned on if VERSION < 1.10.0- or similar?

[lmiq]

However, I'd drop it once 1.10 is officially declared the new LTS.

I would be more conservative. Until most of the dependents migrate their support, I don't see a reason to not support previous version. It is not that we are using any new feature, really.