Update Project.toml to use openspecfun 0.5.5 and julia 1.6

[ViralBShah]

This PR bumps the Julia minimum version to 1.6, in order to use openspecfun v0.5.5 (which pulls in a fix for JuliaPackaging/BinaryBuilderBase.jl#92).

I am considering bumping the SpecialFunctions.jl version to 1.5, so that Julia 1.6 and higher can continue to lower bound and always pick up the fixed openspecfun. There are no reported problems that necessitate the fix, so older releases should continue to be fine. We just pick this up going forward.

[giordano]

Following up from #323

I do need to drop older versions, so that I can force using openspecfun v0.5.5

But we don't need to force it, the package manager will naturally pick it up. OpenSpecFun_jll is only used directly by this package, so there isn't even the risk of having incompatibilities between different packages. I don't think we need to drop versions before 1.6 at this time

[ViralBShah]

That's what I thought too, but something was pinning openspecfun to 0.5.3 on Julia 1.3. Any thoughts how to do this better?

https://github.com/JuliaMath/SpecialFunctions.jl/runs/2727511037

[giordano]

Something was pinning openspecfun to 0.5.3 on Julia 1.3. Any thoughts how to do this better?

New versions (since v0.5.4) of OpenSpecFun_jll do require Julia v1.6, to make it possible to build for aarch64-apple-darwin: JuliaPackaging/Yggdrasil#2892. So no, for older versions of Julia there is no way to convince it to pick up v0.5.5

[ViralBShah]

Does GHA have arm builds? If so, we can reduce the dependency on drone. I suppose travis is good to have for freebsd.

[ViralBShah]

So now the failure is only on armv7. Seems like travis is going away in a couple of weeks - is it straightforward to migrate it to .com?

[ViralBShah]

It turns out that we don't need any of this. Closing.