Fix/226 julia manual download

[WardBrian]

This closes #226 and brings the Julia interface in line with the others by storing the bridgestan sources in ~/.bridgestan

A couple things worth noting:

• Julia's expanduser function does nothing on Windows. I've added a helper function to get the home directory based on what Python does
• This adds a few "dependencies": Tar, TOML, Downloads, and Inflate. I use the scare quotes because all except for Inflate are built in to Julia. Inflate, meanwhile, is used in examples in Julia's documentation, and seems very stable.

[WardBrian]

Ok, so Julia's Tar library didn't support hardlinks until Julia 1.7: JuliaIO/Tar.jl#102

I've updated the release action to generate tarballs without them (it's just a single extra copy of bridgestan.h), but in the mean time the Julia 1.6 test will stay failing. Not really sure what to do

[WardBrian]

I confirmed that adding --hard-dereference to our packaging step produces a tarball which julia 1.6 can read.

So, we can either:

• merge this while it is failing, knowing the next release will actually be fine
• merge just the release.yml change to add that flag, make a small release, and then merge the Julia changes

[roualdes]

This looks good. And thanks for finding a fix that includes Julia 1.6. Since 1.6 is the LTS version, it seems right to include it.

I guess it's better to get this fix out there, and then tidy 1.6 issues later, since this PR started based on a reported issue with Julia 1.10, and not an issue related to 1.6. Maybe that's wrong, but that's my thought.