chore: Update .repo-metadata.json

Author: averikitsch

.repo-metadata.json

@@ -2,12 +2,11 @@
     "name": "langchain-google-spanner",
     "name_pretty": "Cloud Spanner for LangChain - Python",
     "issue_tracker": "https://github.com/googleapis/langchain-google-spanner-python/issues",
-    "client_documentation": "",
     "release_level": "preview",
     "language": "python",
     "library_type": "OTHER",
     "repo": "googleapis/langchain-google-spanner-python",
     "distribution_name": "langchain-google-spanner",
     "requires_billing": true,
     "codeowner_team": "@googleapis/senseai-eco"
-}
+}