remove HTTParty::AllowedFormatsDeprecation

Remove warnings about deprecated ```HTTParty::AllowedFormats``` 
because [there are 5 years since this commit.](https://github.com/jnunemaker/httparty/commit/d0d88fecfdd7528fa8bd8d12004f686318f3486c)
(now nobody knows about ```HTTParty::AllowedFormats``` ,
 all use ```HTTParty::Parser::SupportedFormats```