Heat olive oil in a large Dutch oven over medium heat. Add onion; sauté 5 minutes. Add garlic; sauté 1 minute. Add chicken broth; bring to a boil. Stir in green beans, and bring to a boil; cook 3 minutes. Add zucchini, yellow squash, and corn. Bring to a boil, and cook 4 minutes or until vegetables are tender. Stir in tomatoes; bring to a boil. Remove from heat; stir in basil, salt, and pepper.