Enable newly released Med Gemma 1.5 4B variant version to hub (keras-team#2524)

* Enable newly released medgemma 1.5 version to hub

* Fix Format issue

* Update presets description

* Fix Format

Author: laxmareddyp

keras_hub/src/models/gemma3/gemma3_presets.py

@@ -181,12 +181,25 @@
         },
         "kaggle_handle": "kaggle://keras/gemma3/keras/gemma3_instruct_270m/4",
     },
+    "medgemma_4b": {
+        "metadata": {
+            "description": (
+                "A 4 billion parameter model based on Gemma 3. "
+                "This model is pre-trained for performance on medical text "
+                "and image comprehension and is optimized for medical "
+                "applications that involve a text generation component."
+            ),
+            "params": 4300079472,
+            "path": "gemma3",
+        },
+        "kaggle_handle": "kaggle://keras/medgemma/keras/medgemma_4b/1",
+    },
     "medgemma_instruct_4b": {
         "metadata": {
             "description": (
                 "A 4 billion parameter model based on Gemma 3. "
-                "This model is trained for performance on medical text"
-                "and image comprehension and is optimized for medical"
+                "This model is instruction-tuned for performance on medical "
+                "text and image comprehension and is optimized for medical "
                 "applications that involve a text generation component."
             ),
             "params": 4300079472,
@@ -198,8 +211,8 @@
         "metadata": {
             "description": (
                 "A 27 billion parameter model based on Gemma 3. "
-                "This model trained for performance on medical text "
-                "and image comprehension and is optimized for medical "
+                "This model is instruction-tuned for performance on medical "
+                " text and image comprehension and is optimized for medical "
                 "applications that involve a text generation component."
             ),
             "params": 27432406640,
@@ -211,15 +224,26 @@
         "metadata": {
             "description": (
                 "A 27 billion parameter text-only model based on Gemma 3. "
-                "This model is trained for performance on medical text "
-                "comprehension and is optimized for medical applications "
-                "that involve a text generation component."
+                "This model is instruction-tuned (No images) for performance "
+                "on medical text comprehension and is optimized for medical "
+                "applications that involve a text generation component."
             ),
             "params": 27009002240,
             "path": "gemma3",
         },
         "kaggle_handle": "kaggle://keras/medgemma/keras/medgemma_instruct_27b_text/1",
     },
+    "medgemma_1.5_instruct_4b": {
+        "metadata": {
+            "description": (
+                "A 4 billion parameter,Instruct-tuned MedGemma 1.5 4B is an "
+                "updated version of the Instruction-tuned MedGemma 4B model."
+            ),
+            "params": 4300079472,
+            "path": "gemma3",
+        },
+        "kaggle_handle": "kaggle://keras/medgemma/keras/medgemma_1.5_instruct_4b/1",
+    },
     "function_gemma_instruct_270m": {
         "metadata": {
             "description": (