Add `optional-dependencies` in `pyproject.toml`

[Viicos]

The draft module makes use of pycryptodome, adding this section in the pyproject.toml allows user to install the dependency this way:

pip install joserfc[drafts]

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (6bc0fd4) 99.32% compared to head (42f3633) 99.32%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1 +/- ## ======================================= Coverage 99.32% 99.32% ======================================= Files 46 46 Lines 2365 2365 Branches 358 358 ======================================= Hits 2349 2349 Misses 8 8 Partials 8 8 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `99.32% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=authlib#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.