fix: correct torch dependency syntax in pyproject.toml

Author: liuruibin

pyproject.toml

@@ -29,7 +29,7 @@ dependencies = [
     "langchain-huggingface==0.3.0",
     "langchain-ollama==0.3.4",
     "langgraph==0.5.3",
-    "torch=2.8.0",
+    "torch==2.8.0",
     "sentence-transformers==5.0.0",
     "qianfan==0.4.12.3",
     "zhipuai==2.1.5.20250708",