fix: dont use deprecated models

[daniel-cohere]

This PR updates the model parameter in various test functions across multiple files. The changes involve replacing the existing model names with the new model name "command-a-03-2025".

Changes:

• In tests/test_async_client.py, the model parameter in the following functions is updated to "command-a-03-2025":
  • test_chat
  • test_chat_stream
  • test_tokenize
  • test_detokenize
  • test_tool_use
  • test_local_tokenize
  • test_local_detokenize
  • test_tokenize_async_context_with_sync_client
• In tests/test_client.py, the model parameter in the following functions is updated to "command-a-03-2025":
  • test_tokenize
  • test_detokenize
  • test_tool_use
  • test_local_tokenize
  • test_local_detokenize
• In tests/test_client_v2.py, the model parameter in the following functions is updated to "command-a-03-2025":
  • test_chat
  • test_chat_stream
  • test_chat_documents
  • test_chat_tools

Additionally, the test_summarize and test_connectors_crud functions are removed from both tests/test_async_client.py and tests/test_client.py.