July 21 (Reuters) - Paycor HCM Inc’s shares rose more than 20% in their Nasdaq debut on Wednesday, giving the human capital management firm backed by private equity firm Apax Partners a valuation of $4.8 billion. The stock opened at $28 per share, above the IPO price of $23 each. (Reporting by Sohini Podder; Editing by Ramakrishnan M.)