🐛 Fix release pipeline. (#17)

GitHub workflows' `set-output` command uses the OS's EOL character for
ending the capture, which means `\n` characters must be replaced with
something else. The community wisdom is `%0A`; see actions/toolkit#403.

The `${{ github.repository }}` expression's `/` delimiter conflicts with
the `sed` delimiter; avoid this by changing the `sed` delimiter to `#`.

Release 0.1.0