Pass2csv

Refactor packaging: `setup.cfg` was removed and the contents migrated to `pyproject.toml`. Also includes a fix regarding installation with pipx on MacOS (https://github.com/reinefjord/pass2csv/issues/27).

Notable changes:

- Use Unix newlines (\n) instead of DOS style (\r\n)
- Add flag `--version`

There's not been too many bug reports or feature requests for a while, so it might be time to call this version 1. Breaking changes to the CLI will be accompanied by a bump in the major version, and I will be more reluctant in introducing such changes.

Notable changes:

- Setting the store path to a .gpg file now decodes that file instead of doing nothing. PR 17
- Fix `--get-line` which did not work. PR 18
- Specifying an outfile is now mandatory, having your passwords output in plaintext to stdout can be surprising and potentially dangerous behaviour.
- Less spammy and more readable messages.

- Fix crash on failed decode of binary data (14)
- Change `--encoding` to `--encodings` which accepts multiple comma-separated encodings
- Remove the "extend" action for the argument parser, `--exclude` will have to be specified multiple times

Full rewrite, more flexible functionality and better code. Many changes to CLI, breaks backwards compatibility.

Removed Python 3.8-dependent code, making pass2csv compatible with Python >=3.6.