By Miguel Gutierrez, Michael O'Boyle and Dave Graham MEXICO CITY (Reuters) – Mexico's Congress on Thursday passed a package of measures aimed at bolstering the country's weak tax revenues, but only after watering down a plan that is expected to have a moderate impact at best. The bill, which includes higher taxes on the rich as well as levies on junk food and stock market gains, is a central plank of an economic program spanning energy to telecoms that aims to ramp up growth in Latin America's No. 2 economy. Facing a Thursday deadline, the ruling Institutional Revolutionary Party (PRI) pushed the package through with the help of leftist lawmakers, making final tweaks in the Senate to pare back a planned income tax increase. The lower house then gave final approval to the bill that President Enrique Pena Nieto is now expected to sign into law.