Add unit test for patch_vae_tiling_params().

tests/backend/stable_diffusion/test_vae_tiling.py

@@ -0,0 +1,13 @@
+from diffusers.models.autoencoders.autoencoder_kl import AutoencoderKL
+
+from invokeai.backend.stable_diffusion.vae_tiling import patch_vae_tiling_params
+
+
+def test_patch_vae_tiling_params():
+    """Smoke test the patch_vae_tiling_params(...) context manager. The main purpose of this unit test is to detect if
+    diffusers ever changes the attributes of the AutoencoderKL class that we expect to exist.
+    """
+    vae = AutoencoderKL()
+
+    with patch_vae_tiling_params(vae, 1, 2, 3):
+        pass