Fix caption_entities stringify in sendAudio

[Sp3rick]

caption_entities option in sendAudio was not automatically stringified

• [ ] All tests pass
• [ ] I have run npm run doc

Description

References

[Sp3rick]

I close because i see that's miss in every function with option caption_entities, should be done something like _fixReplyMarkup, or copy paste this: if( opts.qs.hasOwnProperty( "caption_entities" ) && Array.isArray(opts.qs.caption_entities) ) { opts.qs.caption_entities = stringify(opts.qs.caption_entities); }

for every function with caption_entities option (yes, i added array check)

[Sp3rick]

moved to #1122