Clean up/cull stale branches?

[TommyMurphyTM1234]

As far as I can see...

• riscv is the effective "master" branch in this repo on which most development occurs and into which development on other branches is merged.
• Only it and 3 other branches are deemed by GitHub to be active:
  • https://github.com/riscv-collab/riscv-openocd/branches/active
• All 62 other branches are deemed by GitHub to be stale - most inactive for years and a few inactive for several 7+ months:
  • https://github.com/riscv-collab/riscv-openocd/branches/stale

Perhaps some or all of these stale branches can be culled in order to avoid confusion - especially confusion between the master branch and the effective "master" branch riscv?