chore(weight-custody-manifest): bump SDK pin to >=0.22.1 (#66)

Track the current published release (validated H100 GPU verifier + fixed
PyPI project URLs). Behavior unchanged; the examples already ran green
against 0.22.x.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: imran-siddique

weight-custody-manifest/requirements.txt

@@ -1,4 +1,4 @@
 # The Weight Custody Manifest reference SDK, from PyPI.
 # Covers the offline examples. provenance_model_signing.py additionally needs the
 # [model-signing] extra: pip install "weight-custody-manifest[model-signing]".
-weight-custody-manifest>=0.21.0
+weight-custody-manifest>=0.22.1