PHOENIX — Rachelle Williams was sick of delivering mail in Indiana winters, so in 2019, she put in for a transfer to Arizona and joined the flood of newcomers who have made Phoenix one of the country’s fastest-growing cities. She was questioning her move this week as the temperature hit 110 degrees for an 11th consecutive day Monday, with no end in sight. Williams wore long sleeves, black gloves and a broad-brimmed visor with flaps covering her neck to deflect the sun as she walked her route. Bu