Changes to Synthesize speech

the text request property's minLength was increased from 0 to 1

the text request property's maxLength was set to 8000

added the new optional request property math_notation

added the new optional header request parameter x-expire-content

added the new auto enum value to the request property language

added the new auto enum value to the request property number_pronunciation_language

added the new nl enum value to the request property language

added the new nl enum value to the request property number_pronunciation_language

added the new sv enum value to the request property language

added the new sv enum value to the request property number_pronunciation_language

added the new optional request property number_pronunciation_language

added the new ar enum value to the request property language

added the new de enum value to the request property language

added the new el enum value to the request property language

added the new fi enum value to the request property language

added the new fr enum value to the request property language

added the new id enum value to the request property language

added the new it enum value to the request property language

added the new ja enum value to the request property language

added the new ko enum value to the request property language

added the new ms enum value to the request property language

added the new no enum value to the request property language

added the new pl enum value to the request property language

added the new pt enum value to the request property language

added the new ru enum value to the request property language

added the new tr enum value to the request property language

added the new vi enum value to the request property language

added the new zh enum value to the request property language

the language request property default value en was removed

removed the enum value auto of the request property language

added the new optional request property word_timestamps