Add security warning for vulnerable PyTorch versions (#123)

This commit adds security warning and tidies up some codes.

TICO-DCO-1.0-Signed-off-by: seongwoo <mhs4670go@naver.com>

Author: mhs4670go

tico/__init__.py

@@ -18,14 +18,25 @@
 from packaging.version import Version
 
 from tico.config import CompileConfigV1, get_default_config
-
 from tico.utils.convert import convert, convert_from_exported_program, convert_from_pt2
 
 # THIS LINE IS AUTOMATICALLY GENERATED BY setup.py
 __version__ = "0.1.0"
 
+MINIMUM_SUPPORTED_VERSION = "2.5.0"
+SECURE_TORCH_VERSION = "2.6.0"
+
+if Version(torch.__version__) < Version(MINIMUM_SUPPORTED_VERSION):
+    warnings.warn(
+        f"TICO officially supports torch>={MINIMUM_SUPPORTED_VERSION}. "
+        f"You are using a lower version of torch ({torch.__version__}). "
+        f"We highly recommend to upgrade torch>={MINIMUM_SUPPORTED_VERSION} to avoid unexpected behaviors."
+    )
 
-if Version(torch.__version__) < Version("2.5.0"):
+if Version(torch.__version__) < Version(SECURE_TORCH_VERSION):
     warnings.warn(
-        f"TICO officially supports torch>=2.5. You are using a lower version of torch ({torch.__version__}). We highly recommend to upgrade torch >= 2.5 to avoid unexpected behaviors."
+        f"Detected PyTorch version {torch.__version__}, which may include known security vulnerabilities. "
+        f"We recommend upgrading to {SECURE_TORCH_VERSION} or later for better security.\n"
+        "Upgrade command: pip install --upgrade torch\n"
+        "For more details, see: https://pytorch.org/security"
     )