feat(vectordb): Milvus vector db Integration (#1996)

* integrate Milvus into Private GPT

* adjust milvus settings

* update doc info and reformat

* adjust milvus initialization

* adjust import error

* mionr update

* adjust format

* adjust the db storing path

* update doc

private_gpt/settings/settings.py

@@ -125,7 +125,7 @@ class LLMSettings(BaseModel):
 
 
 class VectorstoreSettings(BaseModel):
-    database: Literal["chroma", "qdrant", "postgres", "clickhouse"]
+    database: Literal["chroma", "qdrant", "postgres", "clickhouse", "milvus"]
 
 
 class NodeStoreSettings(BaseModel):
@@ -508,6 +508,27 @@ class QdrantSettings(BaseModel):
     )
 
 
+class MilvusSettings(BaseModel):
+    uri: str = Field(
+        "local_data/private_gpt/milvus/milvus_local.db",
+        description="The URI of the Milvus instance. For example: 'local_data/private_gpt/milvus/milvus_local.db' for Milvus Lite.",
+    )
+    token: str = Field(
+        "",
+        description=(
+            "A valid access token to access the specified Milvus instance. "
+            "This can be used as a recommended alternative to setting user and password separately. "
+        ),
+    )
+    collection_name: str = Field(
+        "make_this_parameterizable_per_api_call",
+        description="The name of the collection in Milvus. Default is 'make_this_parameterizable_per_api_call'.",
+    )
+    overwrite: bool = Field(
+        True, description="Overwrite the previous collection schema if it exists."
+    )
+
+
 class Settings(BaseModel):
     server: ServerSettings
     data: DataSettings
@@ -527,6 +548,7 @@ class Settings(BaseModel):
     qdrant: QdrantSettings | None = None
     postgres: PostgresSettings | None = None
     clickhouse: ClickHouseSettings | None = None
+    milvus: MilvusSettings | None = None
 
 
 """