### What this PR does / why we need it?
This PR fixes a `Stale file handle` error that occurs during doctests in
the CI environment. The error appears when loading models from
ModelScope, likely due to issues with network file systems used in CI.
The fix involves setting the `MODELSCOPE_HUB_FILE_LOCK` environment
variable to `false` in the `run_doctests.sh` script. This disables file
locking in the ModelScope hub, which is a common workaround for this
type of file system error.
### Does this PR introduce _any_ user-facing change?
No, this change only affects the CI test execution environment and has
no impact on users.
### How was this patch tested?
This change is validated by the CI pipeline. A successful run of the
doctests indicates that the fix is effective.
Signed-off-by: leo-pony <nengjunma@outlook.com>
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