Let the Space builder own torch/gradio/spaces

The builder already installs torch (pinned <=2.11.0), gradio, uvicorn and
spaces. Pinning a CPU-only torch from a custom index here collided with that
pin and failed the build outright.

requirements.txt

@@ -1,8 +1,6 @@
---extra-index-url https://download.pytorch.org/whl/cpu
-
-gradio
-torch
+# torch, gradio, uvicorn and spaces are installed by the Space builder itself
+# (and torch is pinned there) — declaring them here only creates a resolver
+# conflict, which is what failed the first build.
 transformers>=4.44,<5
 sentencepiece
 sacremoses
-numpy