community[patch]: Make cohere_api_key a SecretStr (#12188)

This PR makes `cohere_api_key` in `llms/cohere` a SecretStr, so that the
API Key is not leaked when `Cohere.cohere_api_key` is represented as a
string.

---------

Signed-off-by: Arun <arun@arun.blog>
Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>

libs/community/tests/integration_tests/llms/test_cohere.py

@@ -2,6 +2,9 @@
 
 from pathlib import Path
 
+from langchain_core.pydantic_v1 import SecretStr
+from pytest import MonkeyPatch
+
 from langchain_community.llms.cohere import Cohere
 from langchain_community.llms.loading import load_llm
 from tests.integration_tests.llms.utils import assert_llm_equality
@@ -14,6 +17,16 @@ def test_cohere_call() -> None:
     assert isinstance(output, str)
 
 
+def test_cohere_api_key(monkeypatch: MonkeyPatch) -> None:
+    """Test that cohere api key is a secret key."""
+    # test initialization from init
+    assert isinstance(Cohere(cohere_api_key="1").cohere_api_key, SecretStr)
+
+    # test initialization from env variable
+    monkeypatch.setenv("COHERE_API_KEY", "secret-api-key")
+    assert isinstance(Cohere().cohere_api_key, SecretStr)
+
+
 def test_saving_loading_llm(tmp_path: Path) -> None:
     """Test saving/loading an Cohere LLM."""
     llm = Cohere(max_tokens=10)