Fix plugins cache

[kaixi-wang]

What changes are proposed in this pull request?

(Please fill in changes proposed in this fix)

How is this patch tested? If it is not, please explain why.

(Details)

Release Notes

Is this a user-facing change that should be mentioned in the release notes?

• [ ] No. You can skip the rest of this section.
• [ ] Yes. Give a description of this change to be included in the release notes for FiftyOne users.

(Details in 1-2 sentences. You can just refer to another PR with a description if this PR is part of a larger change.)

What areas of FiftyOne does this PR affect?

• [ ] App: FiftyOne application changes
• [ ] Build: Build and test infrastructure changes
• [ ] Core: Core fiftyone Python library changes
• [ ] Documentation: FiftyOne documentation changes
• [ ] Other