KeyError when trying to commit offsets using Transactional Producer

**Describe the bug**
When trying to commit offsets with a transactional producer doing ` await producer.send_offsets_to_transaction(offsets, group_id)` there is a sort of race condition where it seems that two background tasks are trying to do the same.

In my application I am using always the same `transactional producer` with always the same `transactional_id`. The commit is being perform one by one rather than in batches.

**Traceback**

```bash
03/11/2025 02:48:03 PM Unexpected error in sender routine
Traceback (most recent call last):
File "/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 176, in _sender_routine
task.result()
File "\examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 367, in _do_txn_offset_commit
await handler.do(node_id)
File "/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 413, in do
retry_backoff = self.handle_response(resp)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 643, in handle_response
offset = self._offsets[tp].offset
~~~~~~~~~~~~~^^^^
KeyError: TopicPartition(topic='local--kstreams-json', partition=0)
```

I have added some logs in `Sender.py` module and I can see that `Sender._do_txn_offset_commit` is being called twice, trying to `commit` the same offset twice for the `TopicPartition` (in this example `offset 62`). As you can see, `offsets` is a `dict` with id `4345275008` which is shared by the 2 tasks.

The first task calls `TxnOffsetCommitHandler.handle_response` which works fine, then it is called again but then the `offsets dict` is empty, which causes the code to crash when it does `offset = self._offsets[tp].offset`.

```python
Beging Sender._do_txn_offset_commit with offsets {TopicPartition(topic='local--kstreams-json', partition=0): OffsetAndMetadata(offset=62, metadata='')}. Dict Offsets id 4345275008

Ending Sender._do_txn_offset_commit with offsets {TopicPartition(topic='local--kstreams-json', partition=0): OffsetAndMetadata(offset=62, metadata='')}. Dict Offsets id 4345275008

Beging Sender._do_txn_offset_commit with offsets {TopicPartition(topic='local--kstreams-json', partition=0): OffsetAndMetadata(offset=62, metadata='')}. Dict Offsets id 4345275008

Ending Sender._do_txn_offset_commit with offsets {TopicPartition(topic='local--kstreams-json', partition=0): OffsetAndMetadata(offset=62, metadata='')}. Dict Offsets id 4345275008

Handle response in TxnOffsetCommitHandler.handle_response for offsets {TopicPartition(topic='local--kstreams-json', partition=0): OffsetAndMetadata(offset=62, metadata='')}. Dict Offsets id 4345275008

03/11/2025 03:00:00 PM Commiting offsets {TopicPartition(topic='local--kstreams-json', partition=0): 62} for group my-group
Handle response in TxnOffsetCommitHandler.handle_response for offsets {}. Offsets id 4345275008

03/11/2025 03:00:00 PM Unexpected error in sender routine
Traceback (most recent call last):
File "/Users/marcosschroh/Projects/kstreams/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 176, in _sender_routine
task.result()
File "/Users/marcosschroh/Projects/kstreams/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 366, in _do_txn_offset_commit
await handler.do(node_id)
File "/Users/marcosschroh/Projects/kstreams/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 412, in do
retry_backoff = self.handle_response(resp)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/marcosschroh/Projects/kstreams/examples/transactions/.venv/lib/python3.12/site-packages/aiokafka/producer/sender.py", line 642, in handle_response
offset = self._offsets[tp].offset
~~~~~~~~~~~~~^^^^
```

**Expected behaviour**
The offset commit with a transactional producer should always work and wait for previous commit to finish in order to start a new one.

**Environment (please complete the following information):**
- aiokafka version: 0.12.0
- Kafka Broker version: 3.7