docs: Spell check fixes (#24217)

**Description:** Spell check fixes for docs, comments, and a couple of
strings. No code change e.g. variable names.
**Issue:** none
**Dependencies:** none
**Twitter handle:** hmartin

libs/core/langchain_core/documents/base.py

@@ -15,7 +15,7 @@ PathLike = Union[str, PurePath]
 class BaseMedia(Serializable):
     """Use to represent media content.
 
-    Media objets can be used to represent raw data, such as text or binary data.
+    Media objects can be used to represent raw data, such as text or binary data.
 
     LangChain Media objects allow associating metadata and an optional identifier
     with the content.

libs/core/tests/unit_tests/language_models/chat_models/test_cache.py

@@ -279,7 +279,7 @@ class CustomChat(GenericFakeChatModel):
 async def test_can_swap_caches() -> None:
     """Test that we can use a different cache object.
 
-    This test verifies that when we fetch teh llm_string representation
+    This test verifies that when we fetch the llm_string representation
     of the chat model, we can swap the cache object and still get the same
     result.
     """