1.Place diced tomatoes and brown sugar into the cooker insert; stir to combine.
2.Heat 2 tablespoons olive oil in a skillet over medium-high heat, and cook and stir onion until lightly browned, 10 minutes. Add the ginger, cinnamon, cumin, and coriander; cook and stir until the spices release their fragrance, about 2 minutes.
3.Sprinkle flour over chicken and mix well. Add the chicken into the pot and stir. Cook until chicken is no longer pink. Mix the garbanzo beans, 1/2 teaspoon salt, and 1/4 teaspoon pepper into the chicken mixture, and bring to a simmer. Transfer the mixture into the slow cooker, and mix.
3.Add 1 tablespoon olive oil and place pumpkin into the same skillet, and reduce heat to medium. Cook until the pumpkin is hot and some pieces are slightly browned, about 10 minutes, stirring often. Place pumpkin into the slow cooker, stir, and cover.
4.Cook the stew on the high setting for 1 hour; reduce cooker setting to low, and cook until pumpkin is tender, 3 to 4 more hours. Season with salt and black pepper.