By Lucia Mutikani WASHINGTON (Reuters) – U.S. factory activity grew at its slowest pace in more than 1-1/2 years in April amid a rise in workers quitting their jobs, and manufacturers are becoming more anxious about supply over the summer because of China’s zero tolerance COVID-19 policy. The Institute for Supply Management’s (ISM) Manufacturing Business Survey Committee Chair Timothy Fiore said on Monday that coronavirus outbreaks overseas were “creating a near-term headwind for the U.S. manufacturing community,” noting that some manufacturers worried “about their Asian partners’ ability to d…