Bill Cosbyis 86 years old and knows his time is near — but he’s not racing to the finish line to tell all in a memoir; however, his publicist is! Despite a sensational new report that the embattled comedian is planning to tell his side of his sex monster story, RadarOnline.com has discovered that it’s his longtime rep, Andrew Wyatt, who is working on a book. Speculation about a Cosby tell-all began after sources claimed the aging disgraced star “has been working on his memoir for some time,” with an insider telling the National Enquirer that “his pace has increased as his health has deteriorat…