Update Cohere Reranker (#4180)

The forward ref annotations don't get updated if we only iimport with
type checking

---------

Co-authored-by: Abhinav Verma <abhinav_win12@yahoo.co.in>

tests/integration_tests/retrievers/document_compressors/test_cohere_reranker.py

@@ -0,0 +1,8 @@
+"""Test the cohere reranker."""
+
+from langchain.retrievers.document_compressors.cohere_rerank import CohereRerank
+
+
+def test_cohere_reranker_init() -> None:
+    """Test the cohere reranker initializes correctly."""
+    CohereRerank()