Fix index when installing torch through smart build (#449)

Torch changed something in their indexing when trying to install from
their provided wheels. This updates the `pip install` command within
`smart build` to ensure that the appropriate packages can be found.

[ committed by @ashao ]
[ reviewed by @ankona ]

smartsim/_core/_cli/build.py

@@ -226,9 +226,10 @@ def build_redis_ai(
         logger.info("ML Backends and RedisAI build complete!")
 
 
-def check_py_torch_version(versions: Versioner, device: _TDeviceStr = "cpu") -> None:
+def check_py_torch_version(versions: Versioner, device_in: _TDeviceStr = "cpu") -> None:
     """Check Python environment for TensorFlow installation"""
 
+    device = device_in.lower()
     if BuildEnv.is_macos():
         if device == "gpu":
             raise BuildError("SmartSim does not support GPU on MacOS")
@@ -260,10 +261,11 @@ def check_py_torch_version(versions: Versioner, device: _TDeviceStr = "cpu") ->
             "Torch version not found in python environment. "
             "Attempting to install via `pip`"
         )
+        wheel_device = device if device == "cpu" else device_suffix.replace("+","")
         pip(
             "install",
-            "-f",
-            "https://download.pytorch.org/whl/torch_stable.html",
+            "--extra-index-url",
+            f"https://download.pytorch.org/whl/{wheel_device}",
             *(f"{package}=={version}" for package, version in torch_deps.items()),
         )
     elif missing or conflicts: