Allow S3 openapi to be nullable

[Rados13]

Acknowledging the stipulations set forth:

• [x] I hereby confirm that a Pull Request involving updates to the Software Development Kit (SDK) has been smoothly merged, currently awaits processing, or is otherwise deemed unnecessary in this context.
• [x] I also affirm that another Pull Request, specifically addressing updates to the documentation body (commonly referred to as 'docs'), has either been successfully incorporated, is in the process of review, or is considered superfluous under the prevailing circumstances.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.77%. Comparing base (b76e35b) to head (26c7814).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #209 +/- ## ======================================= Coverage 86.77% 86.77% ======================================= Files 79 79 Lines 1573 1573 ======================================= Hits 1365 1365 Misses 208 208 ``` | [Files](https://app.codecov.io/gh/fishjam-dev/fishjam/pull/209?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev) | Coverage Δ | | |---|---|---| | [lib/fishjam\_web/api\_spec/component/HLS/S3.ex](https://app.codecov.io/gh/fishjam-dev/fishjam/pull/209?src=pr&el=tree&filepath=lib%2Ffishjam_web%2Fapi_spec%2Fcomponent%2FHLS%2FS3.ex&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev#diff-bGliL2Zpc2hqYW1fd2ViL2FwaV9zcGVjL2NvbXBvbmVudC9ITFMvUzMuZXg=) | `100.00% <ø> (ø)` | | ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/fishjam-dev/fishjam/pull/209?dropdown=coverage&src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/fishjam-dev/fishjam/pull/209?dropdown=coverage&src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev). Last update [b76e35b...26c7814](https://app.codecov.io/gh/fishjam-dev/fishjam/pull/209?dropdown=coverage&src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fishjam-dev).