cli[minor]: Add __version__ to integration package template (#19876)

Packages should export __version__

libs/cli/langchain_cli/integration_template/integration_template/__init__.py

@@ -1,11 +1,21 @@
+from importlib import metadata
+
 from __module_name__.chat_models import Chat__ModuleName__
 from __module_name__.embeddings import __ModuleName__Embeddings
 from __module_name__.llms import __ModuleName__LLM
 from __module_name__.vectorstores import __ModuleName__VectorStore
 
+try:
+    __version__ = metadata.version(__package__)
+except metadata.PackageNotFoundError:
+    # Case where package metadata is not available.
+    __version__ = ""
+del metadata  # optional, avoids polluting the results of dir(__package__)
+
 __all__ = [
-    "__ModuleName__LLM",
     "Chat__ModuleName__",
+    "__ModuleName__LLM",
     "__ModuleName__VectorStore",
     "__ModuleName__Embeddings",
+    "__version__",
 ]