👌 IMPROVE: links to materials cloud SSSP archive

[mbercx]

Fixes #13

The current links used to download the SSSP pseudopotentials still point to the legacy materials cloud archive, which are hosted on a server that they want to shut down. Next to this, the archive now also contains new patch versions for minor version 1.1, with 1.1.2 being the latest. Since these patch versions usually implement bug fixes, there is no reason to install an outdated patch version. So instead of allowing the user to install specific patch versions, we'll simply stick to only using minor versions and make sure that the latest patch version is installed.

Here we update the links to the new servers. However, we also add some extra functionality to retrieve a mapping of the latest patch version corresponding to the minor version of the configuration. Based on this mapping, the correct url is constructed for the archive and metadata.

[mbercx]

@sphuber the links in this PR are still for the staging version of the archive, since we wanted to test this before @vgranata puts this in production.

If you agree with the implementation, I'll ask @vgranata to move forward, then update the final links and fix the tests.

[mbercx]

Thanks for the review, @sphuber! I made some first corrections, but have a look at this comment and see if you agree with my reasoning here before I continue.

[mbercx]

(aiida-pseudo) mbercx@theospc46:~/envs/aiida-pseudo/code/aiida-pseudo$ git commit -a
Fix double quoted strings................................................Passed
Fix End of Files.........................................................Passed
Fix python encoding pragma...............................................Passed
Mixed line ending........................................................Passed
Trim Trailing Whitespace.................................................Passed
flynt....................................................................Passed
yapf.....................................................................Passed
pylint...................................................................Passed
pydocstyle...............................................................Passed
[fix/13/materialscloud-links 8874770] Apply more corrections from prime ape instance
 2 files changed, 4 insertions(+), 6 deletions(-)

[sphuber]

Fixed the CI issues in #105

[mbercx]

@sphuber I've removed the md5 hashes and the version from the test_sssp_install test, since these will depend on the patch version. I.e. if this is updated on the archive, the test will start to fail.

[sphuber]

Thanks @mbercx