chore: + the linter `mypy` as a pre-commit hook (#9791)

.pre-commit-config.yaml

@@ -34,6 +34,20 @@ repos:
         name: black-src
         alias: black
         exclude: ^(docs/|llama_index/_static)
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v1.0.1
+    hooks:
+      - id: mypy
+        additional_dependencies:
+          [
+            "types-requests",
+            "types-Deprecated",
+            "types-redis",
+            "types-setuptools",
+            "types-PyYAML",
+            "types-protobuf",
+          ]
+        exclude: ^(docs/|llama_index/_static)
   - repo: https://github.com/psf/black-pre-commit-mirror
     rev: 23.10.1
     hooks:

llama_index/embeddings/pooling.py

@@ -25,7 +25,9 @@ class Pooling(str, Enum):
 
     @classmethod
     @overload
-    def cls_pooling(cls, array: "torch.Tensor") -> "torch.Tensor":
+    # TODO: Remove this `type: ignore` after the false positive problem
+    #  is addressed in mypy: https://github.com/python/mypy/issues/15683 .
+    def cls_pooling(cls, array: "torch.Tensor") -> "torch.Tensor":  # type: ignore
         ...
 
     @classmethod

tests/vector_stores/test_elasticsearch.py

@@ -87,6 +87,7 @@ def elasticsearch_connection() -> Union[dict, Generator[dict, None, None]]:
         if index_name.startswith("test_"):
             es.indices.delete(index=index_name)
     es.indices.refresh(index="_all")
+    return {}
 
 
 @pytest.fixture(scope="session")