dev(narugo): add safety action

[narugo1992]

from waifuc.action import SafetyAction
from waifuc.export import SaveExporter
from waifuc.source import DanbooruSource

s = DanbooruSource(['mukaino_kei', 'unicorn_(azur_lane)'])
s.attach(
    SafetyAction()
)[:40].export(SaveExporter('test_safety', no_meta=True))

[codecov[bot]]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (aca20c7) 67.00% compared to head (4300d41) 67.04%.

Files	Patch %	Lines
waifuc/action/safety.py	75.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #19 +/- ## ========================================== + Coverage 67.00% 67.04% +0.04% ========================================== Files 42 43 +1 Lines 2085 2094 +9 ========================================== + Hits 1397 1404 +7 - Misses 688 690 +2 ``` | [Flag](https://app.codecov.io/gh/deepghs/waifuc/pull/19/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepghs) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/deepghs/waifuc/pull/19/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepghs) | `67.04% <77.77%> (+0.04%)` | :arrow_up: | 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=deepghs#carryforward-flags-in-the-pull-request-comment) to find out more.

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