Heat olive oil in a large skillet over medium heat. Cook the green and red peppers and onions 8 to 10 minutes. Add garlic and sauté 1 minute more. Place the mixture into a slow cooker. Stir in corn, zucchini, yellow squash, chili powder, smoked paprika, cumin, oregano, parsley, salt, black pepper, tomatoes, black beans, canellini beans. kidney beans, and tomato paste until thoroughly mixed. Stir in vegetable broth. Set the cooker on Low, and cook until all vegetables are tender, 4 to 5 hours. Check seasoning; if chili is too thick, add more vegetable broth to desired thickness. Cook an additional 1 to 2 hours to blend the flavors.