Fix warnings on Windows

[ehuss]

This fixes some warnings that show up on Windows:

warning: unused variable: `path`
    --> tests\testsuite\registry.rs:3146:24
     |
3146 |     fn set_permissions(path: &Path, permissions: u32) {
     |                        ^^^^ help: if this is intentional, prefix it with an underscore: `_path`
     |
     = note: `#[warn(unused_variables)]` on by default

warning: unused variable: `permissions`
    --> tests\testsuite\registry.rs:3146:37
     |
3146 |     fn set_permissions(path: &Path, permissions: u32) {
     |                                     ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_permissions`

[rustbot]

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[epage]

Feel free to merge when CI is green