Unpin spaces (platform force-installs its version); keep peft==0.19.1

The ZeroGPU builder appends spaces==<current> to pip install, so any
spaces pin is ResolutionImpossible by construction. The runtime
regression pin that matters is peft==0.19.1.

requirements.txt

@@ -1,11 +1,11 @@
 gradio==6.13.0
-# Pinned 2026-08-11: spaces 0.51.x + peft 0.20.0 (both released after the
-# last successful build) broke ZeroGPU startup with 'No CUDA GPUs are
-# available' in peft's load_peft_weights (direct-to-cuda safetensors load
-# that the ZeroGPU emulator cannot service in the main process). These are
-# the last-known-good versions from the 2026-06-20 build.
-spaces==0.50.4
+# spaces MUST float: the ZeroGPU builder force-appends the platform's
+# current version to pip (pinning it -> ResolutionImpossible at build).
+spaces
 transformers>=5.7.0
+# peft pinned 2026-08-11: 0.20.0 (2026-07-28) loads adapter safetensors
+# directly onto cuda, which the ZeroGPU main-process emulator cannot
+# service -> 'RuntimeError: No CUDA GPUs are available' at startup.
 peft==0.19.1
 # Pin torch so the flash-attn wheel ABI below matches. 2.8.0 is the
 # lowest version ZeroGPU currently accepts (supported: 2.8/2.9/2.10/