Add Aqua.jl quality tests

[PatrickHaecker]

• Add Aqua to test extras with compat bound
• Add compat entries for StructTypes and Test (fixes Aqua's test_deps_compat extras check)
• Run Aqua.test_all in runtests.jl at the last test as it takes much longer than other tests so that errors are found quickly

This addresses a part of #21 (review).

[PatrickHaecker]

Adding Aqua.jl was smooth, as only the compat entries were missing to make Aqua happy. However, based on my experience with JET in the showrepr path, I fear that JET will be more complicated. We'll see, but that's why I go with two separate PRs.

[PatrickHaecker]

By the way, it's not the first time I needed to jump through some loops to support older Julia versions. As Julia 1.6 is no longer supported, maybe you want to consider to rise the minimum requirement to 1.10.

That being said, the workaround here would also have been necessary for 1.10 and overall it's not too much code, so it doesn't matter too much. However, at least testing Julia 1.10 on CI probably makes sense either way, independent of dropping 1.6 or not.

[jw3126]

Yes feel free to bump min julia version to 1.10 or even higher.

[PatrickHaecker]

Ok, thanks. Good to know that dropping 1.6 is an option. I currently would not drop 1.10, as a lot of users prefer that version compared to 1.12 due to lower latency.