feat: add parameter for output image resolution (#13519)

* feat: add parameter for output image resolution

* fix: spacing

* fix: update genai version

* fix: add config

Author: katiemn

genai/image_generation/imggen_with_txt.py

@@ -18,6 +18,7 @@
 def generate_images(output_file: str) -> Image:
     # [START googlegenaisdk_imggen_with_txt]
     from google import genai
+    from google.genai.types import GenerateImagesConfig
 
     client = genai.Client()
 
@@ -27,6 +28,9 @@ def generate_images(output_file: str) -> Image:
     image = client.models.generate_images(
         model="imagen-4.0-generate-preview-06-06",
         prompt="A dog reading a newspaper",
+        config=GenerateImagesConfig(
+            image_size="2K",
+        ),
     )
 
     image.generated_images[0].image.save(output_file)