Make metadata deserialization failures non-fatal in the cache (#11105)
## Summary
If we fail to deserialize cached metadata in the cache, we should just
ignore it, rather than failing.
Ideally, this never happens. If it does, it means we missed a cache
version bump. But if it does happen, it should still be non-fatal.
Closes https://github.com/astral-sh/uv/issues/11043.
Closes https://github.com/astral-sh/uv/issues/11101.
## Test Plan
Prior to this PR, the following would fail:
- `uvx uv@0.5.25 venv --python 3.12 --cache-dir foo`
- `uvx uv@0.5.25 pip install ./scripts/packages/hatchling_dynamic
--no-deps --python 3.12 --cache-dir foo`
- `uvx uv@0.5.18 venv --python 3.12 --cache-dir foo`
- `uvx uv@0.5.18 pip install ./scripts/packages/hatchling_dynamic
--no-deps --python 3.12 --cache-dir foo`
We can't go back and fix 0.5.18, but this will prevent such regressions
in the future.