Refactor image generation code with dynamic size and model

The commit modifies the image generation code in the OpenAI class. The size and model of the generated image can now be dynamically set based on the provided prompt. The code has been refactored to handle different image sizes and models correctly.

src/gptbot/classes/openai.py

@@ -225,13 +225,27 @@ Only the event_types mentioned above are allowed, you must not respond in any ot
         """
         self.logger.log(f"Generating image from prompt '{prompt}'...")
 
+        split_prompt = prompt.split()
+
+        size = "1024x1024"
+
+        if self.image_model == "dall-e-3":
+            if split_prompt[0] == "--portrait":
+                size = "1024x1792"
+                prompt = " ".join(split_prompt[1:])
+            elif split_prompt[0] == "--landscape":
+                size = "1792x1024"
+                prompt = " ".join(split_prompt[1:])
+
+        self.logger.log(f"Generating image with size {size} using model {self.image_model}...")
+
         image_partial = partial(
             self.openai_api.images.generate,
                 model=self.image_model,
                 quality="standard" if self.image_model != "dall-e-3" else "hd",
                 prompt=prompt,
                 n=1,
-                size="1024x1024",
+                size=size,
                 user=user,
         )
         response = await self._request_with_retries(image_partial)