[#250] Make -cache work with relative path.

[williambrode]

Description:

Fixes #(issue)

Checklist:

• [ ] Tests included.
• [ ] Lint and formatter run with no errors.
• [ ] Tests all pass.

Where applicable:

• [ ] Public APIs match existing style.
• [ ] Any breaking changes have a deprecation path or have been discussed.
• [ ] Updated the vendor folder (using go mod vendor).