9.0.0: Merge pull request #12 from Mathics3/release-9.0

Support Python 3.13. Remove support for Python 3.8 and Python 3.9.
Revise for new location API and 9.0.0 release.

• added debugger commands:
  • abort
  • info program
  • set return
  • quit
• Improve Element printing
  • Handle Slot[x] -> #x
  • add unary precedence
• Add DebugEvaluation[] Builtin Function
• TraceEvaluation[] improvements:
  • Returning x <- tuple(y) becomes Replacing x -> y
  • Show locations on TraceEvaluation[]
• Show Mathics3 source location sometimes when $TrackLocaitons is set.
• respect TREPAN_PYGMENTS_STYLE for setting pygments style