One of New Jersey’s most powerful lawmakers is calling on the state Department of Education to open a formal investigation into a charter school network accused of nepotism and paying its executives what have been described as “astonishing” salaries. State Sen. Vin Gopal, D-Monmouth, and chairman of the Senate Education Committee, called for the inquiry in a letter sent Wednesday to acting state Education Commissioner Kevin Dehmer and obtained by NJ Advance Media. In the letter, Gopal cited an NJ Advance Media investigation from last week that showed executives from College Achieve Public Scho…