Fix typo in property name (#17365)

* Fix typo in property name

Fixes the following error:

```
AttributeError: 'OpensearchVectorClient' object has no attribute 'os_version'
Python stacktrace:
 [1] _is_efficient_filtering_enabled
   @ llama_index.vector_stores.opensearch.base ~/.cache/pypoetry/virtualenvs/rag-company-rules-q2Dy5nHQ-py3.11/lib/python3.11/site-packages/llama_index/vector_stores/opensearch/base.py:637
 [2] __init__
   @ llama_index.vector_stores.opensearch.base ~/.cache/pypoetry/virtualenvs/rag-company-rules-q2Dy5nHQ-py3.11/lib/python3.11/site-packages/llama_index/vector_stores/opensearch/base.py:126
```

* Bump version

llama-index-integrations/vector_stores/llama-index-vector-stores-opensearch/llama_index/vector_stores/opensearch/base.py

@@ -634,7 +634,7 @@ def _is_efficient_filtering_enabled(self) -> bool:
             ef_enabled = False
         else:
             self._os_version = self._get_opensearch_version()
-            major, minor, patch = self.os_version.split(".")
+            major, minor, patch = self._os_version.split(".")
             ef_enabled = int(major) >= 2 and int(minor) >= 9
         return ef_enabled
 

llama-index-integrations/vector_stores/llama-index-vector-stores-opensearch/pyproject.toml

@@ -27,7 +27,7 @@ exclude = ["**/BUILD"]
 license = "MIT"
 name = "llama-index-vector-stores-opensearch"
 readme = "README.md"
-version = "0.5.1"
+version = "0.5.2"
 
 [tool.poetry.dependencies]
 python = ">=3.9,<4.0"