Add Nano Banana 2 (gemini-3.1-flash-image-preview) (pydantic#4525)

Author: adtyavrdhn

pydantic_ai_slim/pydantic_ai/models/__init__.py

@@ -251,6 +251,7 @@
         'gateway/google-vertex:gemini-3-flash-preview',
         'gateway/google-vertex:gemini-3-pro-image-preview',
         'gateway/google-vertex:gemini-3-pro-preview',
+        'gateway/google-vertex:gemini-3.1-flash-image-preview',
         'gateway/google-vertex:gemini-3.1-flash-lite-preview',
         'gateway/google-vertex:gemini-3.1-pro-preview',
         'gateway/google-vertex:gemini-flash-latest',
@@ -368,6 +369,7 @@
         'google-gla:gemini-3-flash-preview',
         'google-gla:gemini-3-pro-image-preview',
         'google-gla:gemini-3-pro-preview',
+        'google-gla:gemini-3.1-flash-image-preview',
         'google-gla:gemini-3.1-flash-lite-preview',
         'google-gla:gemini-3.1-pro-preview',
         'google-gla:gemini-flash-latest',
@@ -383,6 +385,7 @@
         'google-vertex:gemini-3-flash-preview',
         'google-vertex:gemini-3-pro-image-preview',
         'google-vertex:gemini-3-pro-preview',
+        'google-vertex:gemini-3.1-flash-image-preview',
         'google-vertex:gemini-3.1-flash-lite-preview',
         'google-vertex:gemini-3.1-pro-preview',
         'google-vertex:gemini-flash-latest',

pydantic_ai_slim/pydantic_ai/models/google.py

@@ -121,8 +121,9 @@
     'gemini-2.5-flash-lite-preview-09-2025',
     'gemini-2.5-pro',
     'gemini-3-flash-preview',
-    'gemini-3-pro-preview',
     'gemini-3-pro-image-preview',
+    'gemini-3-pro-preview',
+    'gemini-3.1-flash-image-preview',
     'gemini-3.1-flash-lite-preview',
     'gemini-3.1-pro-preview',
 ]