Former US president Donald Trump on Sunday called on the United States to “stand united” after surviving an assassination attempt at a campaign rally in Pennsylvania. The 78-year-old, who is running to dethrone his successor President Joe Biden in November’s election, was shot in the ear during the incident in Butler, north of Pittsburgh, on Saturday. One spectator was killed and two critically injured, while the shooter – named by the FBI as 20-year-old Thomas Matthew Crooks – was killed by US Secret Service agents. Writing on his social media platform Truth Social on Sunday, Trump said “it w…