SPRINGFIELD — Gov. J.B. Pritzker signed his first budget into law Wednesday — alongside another measure that puts in place a graduated income structure if his tax plan passes the 2020 ballot referendum.Lawmakers passed a $40.1 billion state budget with bipartisan support during the final days of the legislative session. Additionally, they passed a constitutional amendment proposal that will allow voters to decide if they want to change the income tax structure residents pay annually from a flat rate to a …