pass list of strings to embed method in tf_hub (#3284)

This fixes the below mentioned issue. Instead of simply passing the text
to `tensorflow_hub`, we convert it to a list and then pass it.
https://github.com/hwchase17/langchain/issues/3282

Co-authored-by: Prakhar Agarwal <i.prakhar-agarwal@devrev.ai>

langchain/embeddings/tensorflow_hub.py

@@ -66,5 +66,5 @@ class TensorflowHubEmbeddings(BaseModel, Embeddings):
             Embeddings for the text.
         """
         text = text.replace("\n", " ")
-        embedding = self.embed(text).numpy()[0]
+        embedding = self.embed([text]).numpy()[0]
         return embedding.tolist()