Support the openai moderation adapter

[SimFG]

issue: #366

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[codecov]

Codecov Report

Merging #376 (0067fdc) into dev (09f9107) will decrease coverage by 0.01%.
The diff coverage is 87.23%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #376      +/-   ##
==========================================
- Coverage   93.98%   93.97%   -0.01%     
==========================================
  Files          79       79              
  Lines        2625     2654      +29     
==========================================
+ Hits         2467     2494      +27     
- Misses        158      160       +2     

Impacted Files	Coverage Δ
gptcache/config.py	100.00% <ø> (ø)
gptcache/core.py	91.07% <0.00%> (ø)
gptcache/embedding/huggingface.py	85.71% <ø> (ø)
gptcache/adapter/adapter.py	90.80% <83.33%> (+0.10%)	⬆️
gptcache/adapter/openai.py	92.35% <91.89%> (-0.01%)	⬇️
gptcache/processor/pre.py	100.00% <100.00%> (ø)