Delete irrelevant workshop directories and rename

[github-actions]

• Delete the irrelevant *-workshop folder.
  If your workshop is a virtual workshop, remove the in-person-workshop folder.
  If your workshop is an in-person workshop, remove the virtual-workshop folder.
  • If you're running an in-person workshop, you will not need the virtual-setup folder, either.
• Rename the relevant *-workshop folder to workshop.
  For a virtual workshop, virtual-workshop should be renamed to workshop.
  Changing this folder name will make several links in the repository work –there are instances where we link to a schedule with ../workshop/SCHEDULE.md, for example.