Yet another reason to use `uv`!

I try to avoid bugs like this:

By accident, at first, I omitted the letter u in my list of letters that I was generating packages for, which caused extremely cryptic and long (500KB of uv painstakingly explaining to me why I was wrong) dependency resolution errors on specific guesses:

by doing this:

  import string
  LETTERS = string.ascii_lowercase

instead of this:

  LETTERS = "abcdefghijklmnopqrstuvwxyz"

It's a few more characters to type, but easier to examine for correctness.