fix: Fixes DeprecationWarning when using send method

Merge #3352

Replace send() method with send_realtime_input() to fix DeprecationWarning

### Link to Issue or Description of Change

**1. Link to an existing issue (if applicable):**

- Closes: #2393

### Testing Plan

Have run unit test for test_live_request_queue.py

**Unit Tests:**

- [ ] I have added or updated unit tests for my change.
- [x] All unit tests pass locally.

Summary :

tests/unittests/agents/test_live_request_queue.py::test_send_realtime PASSED                [100%]

**Manual End-to-End (E2E) Tests:**

### Checklist

- [x] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [x] I have performed a self-review of my own code.
- [x] I have commented my code, particularly in hard-to-understand areas.
- [ ] I have added tests that prove my fix is effective or that my feature works.
- [x] New and existing unit tests pass locally with my changes.
- [x] I have manually tested my changes end-to-end.
- [ ] Any dependent changes have been merged and published in downstream modules.

Tested both API variants.

Co-authored-by: Hangfei Lin <hangfei@google.com>
COPYBARA_INTEGRATE_REVIEW=#3352 from SanjaySiddharth:fix-dep-session.send b23b641
PiperOrigin-RevId: 830182844

Author: 2 people

src/google/adk/models/gemini_llm_connection.py

@@ -106,10 +106,10 @@ async def send_realtime(self, input: RealtimeInput):
       input: The input to send to the model.
     """
     if isinstance(input, types.Blob):
-      input_blob = input.model_dump()
       # The blob is binary and is very large. So let's not log it.
       logger.debug('Sending LLM Blob.')
-      await self._gemini_session.send(input=input_blob)
+      await self._gemini_session.send_realtime_input(media=input)
+
     elif isinstance(input, types.ActivityStart):
       logger.debug('Sending LLM activity start signal.')
       await self._gemini_session.send_realtime_input(activity_start=input)

tests/unittests/models/test_gemini_llm_connection.py

@@ -45,7 +45,11 @@ async def test_send_realtime_default_behavior(
   await gemini_connection.send_realtime(test_blob)
 
   # Should call send once
-  mock_gemini_session.send.assert_called_once_with(input=test_blob.model_dump())
+  mock_gemini_session.send_realtime_input.assert_called_once_with(
+      media=test_blob
+  )
+  # Should not call .send function
+  mock_gemini_session.send.assert_not_called()
 
 
 @pytest.mark.asyncio