To cite STV in publications use:

Jay Emerson (2022). STV: Single Transferable Vote Counting. Department of Statistics, Yale University, New Haven, CT. Work in Progress, https://github.com/jayemerson/STV.

You are probably just citing the package at this point.

Corresponding BibTeX entry:

  @Manual{,
    title = {STV: Single Transferable Vote Counting},
    author = {{Jay Emerson}},
    organization = {Department of Statistics, Yale University},
    address = {New Haven, CT},
    year = {2022},
    note = {Work in Progress},
    url = {https://github.com/jayemerson/STV},
  }