WASHINGTON — The Supreme Court on Thursday upheld voting restrictions in Arizona in a decision that could make it harder to challenge other voting measures put in place by Republican lawmakers following last year’s elections. The court, by a 6-3 vote, reversed a lower court ruling in deciding that Arizona’s limits on who can return early ballots for another person and its refusal to count ballots cast in the wrong precinct are not racially discriminatory. The federal appeals court in San Francisco had held that the …