In a large pot over medium-high heat, warm the olive oil. Add the onion, carrot, and celery and sauté until tender, about 5 minutes. Add the garlic and stir until fragrant, 1 minute. Add the stock, tomatoes, chickpeas, frozen vegetables, and bay leaf. Bring to a simmer, adjust the heat to maintain, and cook until the flavors have blended, about 10 minutes. Remove and discard the bay leaf. Ladle the soup into bowls, dollop each with 1 tablespoon pesto, grind with pepper, and serve warm.