Spicy Lamb Shish Kebabs

Name: Spicy Lamb Shish Kebabs
Ingredients: 1/4 cup fat-free plain Greek yogurt; 1 tablespoon hot paprika; 1 teaspoon ground cumin; 1/2 teaspoon ground allspice; 2 garlic cloves, minced; 1 tablespoon extra-virgin olive oil, plus more for brushing; Kosher salt and freshly ground pepper; 2 pounds trimmed lean leg of lamb, cut into 1-inch cubes; 1 pound small zucchini, halved lengthwise and cut crosswise into 1-inch pieces; Warmed pita bread, for serving