Not use the "sync_guard" feature of parking_lot

[nullchinchilla]

dashmap uses the sync_guard feature of parking_lot. However, in my codebase, I use parking_lot throughout, and I intentionally want parking_lot guards to not be Sync, as defense against accidentally keeping them across .await points (which can easily lead to deadlocks).

But I cannot do so unless I downgrade dashmap to v4, because dashmap will turn on the sync_guard feature for me. This has caused several accidental deadlocks in my code already.

Can this be controlled at least by a feature flag? I don't want dashmap Refs to be Sync either.

[xacrimon]

This will be fixed in next v5. V5 is currently yanked due to a vulnerability and I'd recommend downgrading ASAP.

[xacrimon]

Fixed by #179