Fixes compute_output_shape for PaliGemmaVitEncoder and Gemma3VisionEncoderBlock (#2210)

Author: JyotinderSingh

keras_hub/src/models/gemma3/gemma3_vision_encoder.py

@@ -488,7 +488,7 @@ def compute_output_shape(self, inputs_shape):
             # Fix the compatibility issue with Keras 3.1 where
             # `compute_output_spec` fails to propagate `inputs_shape`
             # correctly, causing it to be `None`.
-            inputs_shape = [None, None, None]
+            return [None, None, self.hidden_dim]
         return [
             None,
             (inputs_shape[2] // self.patch_size) ** 2,

keras_hub/src/models/pali_gemma/pali_gemma_vit.py

@@ -329,7 +329,7 @@ def compute_output_shape(self, inputs_shape):
             # Fix the compatibility issue with Keras 3.1 where
             # `compute_output_spec` fails to propagate `inputs_shape`
             # correctly, causing it to be `None`.
-            inputs_shape = [None, None, None]
+            return [None, None, self.hidden_dim]
         return [
             inputs_shape[0],
             (inputs_shape[1] // self.patch_size) ** 2,