Preheat your oven to 350°F (175°C). Grease the loaf pan and line it with parchment paper for easy removal. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside. In a large bowl, whisk together the yogurt, sugar, eggs, and vanilla extract until smooth. Gradually add the dry ingredients to the wet mixture, mixing until just combined. Slowly fold in the vegetable oil until fully incorporated. Gently fold in the diced peaches and raspberries, being careful not to overmix or crush the fruit. Pour the batter into the prepared loaf pan and smooth the top. Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.