Place garlic scapes in food processor and process until finely chopped. Add kale, basil, pumpkin seeds, and nutritional yeast. Pulse until just blended, scraping down sides with a spatula. Add oil, lemon juice, and salt. Blend and taste to adjust seasonings. Use immediately, or store extra in an air-tight container, covered by a layer of olive oil. Pesto can also be frozen for several months.