Gunna got duped into performing at an X Games concert by shady concert promoters who lured him to Colorado with promises of a huge payday that never came ... this according to a new lawsuit. In the suit, obtained by TMZ, Gunna's touring company claims it agreed to have the rapper perform at an X Games event in Aspen back in January ... and signed a contract guaranteeing him $500,000 the night of the gig. The company claims the agreement called for an additional $250,000 payment if he didn't get