community[patch]: fix Chroma add_images (#17964)

###  Description

Fixed a small bug in chroma.py add_images(), previously whenever we are
not passing metadata the documents is containing the base64 of the uris
passed, but when we are passing the metadata the documents is containing
normal string uris which should not be the case.

### Issue

In add_images() method when we are calling upsert() we have to use
"b64_texts" instead of normal string "uris".

### Twitter handle

https://twitter.com/whitepegasus01

libs/community/langchain_community/vectorstores/chroma.py

@@ -209,7 +209,7 @@ def add_images(
                     empty_ids.append(idx)
             if non_empty_ids:
                 metadatas = [metadatas[idx] for idx in non_empty_ids]
-                images_with_metadatas = [uris[idx] for idx in non_empty_ids]
+                images_with_metadatas = [b64_texts[idx] for idx in non_empty_ids]
                 embeddings_with_metadatas = (
                     [embeddings[idx] for idx in non_empty_ids] if embeddings else None
                 )
@@ -231,7 +231,7 @@ def add_images(
                     else:
                         raise e
             if empty_ids:
-                images_without_metadatas = [uris[j] for j in empty_ids]
+                images_without_metadatas = [b64_texts[j] for j in empty_ids]
                 embeddings_without_metadatas = (
                     [embeddings[j] for j in empty_ids] if embeddings else None
                 )