Add docs versioning

[qiaojunfeng]

Use mike to deploy multiple versions of the docs

• This adds a dropdown list in the header of the webpage
  
  

• Old-version pages show warning banners
  

• The default URL redirects to the latest version, for a preview see

  • https://qiaojunfeng.github.io/wannier90/latest/ redirects to https://qiaojunfeng.github.io/wannier90/latest/
  • https://qiaojunfeng.github.io/wannier90/latest/ points to the latest v3.2.0 https://qiaojunfeng.github.io/wannier90/v3.2.0/
  • v3.1.0 can be accessed by https://qiaojunfeng.github.io/wannier90/v3.1.0/

• Added a github workflow to automatically deploy docs when a new release is made

  • For an actual github workflow run, see https://github.com/qiaojunfeng/wannier90/actions/runs/7944463777/job/21690007404

Fix #475
Should be merged after #483