Version prepartion + changelog, FAQ documentation

[jcoulter12]

Summary of changes:

This PR is a bit more mixed than it should be -- however, it includes several small bugfixes that likely do not affect most users, several updates to versions of tooling and from C++17->20, and a few additions to the documentation.

This PR is primarily in service of moving to a more regular versioning pattern.

Minor bugfixes:

• Minor bugfix to Wannier interpolation of band energies when ws_vec file from Wannier90 is used.
• Minor bugfix to the phononLifetimes app -- in some materials, is was possible for a threshold discarding degenerate three phonon triplets based on energies was too loose, meaning real contributions were lost.

Tooling updates

• Update google tests version to 1.14
• Split git actions so that all compiler tests are only run during a PR rather than on each commit
• Upgrade to C++ 20 std

Changes to the documentation:

• Addition of contributors section to "About" page
• New "FAQ and Performance Tips" page of the documentation
• Add "Changelog" page, with a very long update since the 1.0 release
• Update docs to reference the updated phoebe-qe patch to QE 7.3
• Update docs to show version 1.1.0

Thanks also to user @TheoBardu for identifying and testing the fix to the phononLifetimes app issue.