fix(deps): update rust crate which to v7

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
which	dependencies	major	6 -> 7

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Release Notes

harryfei/which-rs (which)

v7.0.0

Compare Source

• Add support to WhichConfig for a user provided closure that will be called whenever a nonfatal error occurs.
  This technically breaks a few APIs due to the need to add more generics and lifetimes. Most code will compile
  without changes.

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Configuration

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: backend/Cargo.lock

Command failed: cargo update --config net.git-fetch-with-cli=true --manifest-path backend/tauri/Cargo.toml --package which@6.0.3 --precise 7.0.0
    Updating crates.io index
error: failed to select a version for the requirement `which = "^6.0"`
candidate versions found which didn't match: 7.0.0
location searched: crates.io index
required by package `luajit-src v210.5.11+97813fb`
    ... which satisfies dependency `luajit-src = ">=210.5.0, <210.6.0"` (locked to 210.5.11+97813fb) of package `mlua-sys v0.6.5`
    ... which satisfies dependency `ffi = "^0.6.5"` (locked to 0.6.5) of package `mlua v0.10.1`
    ... which satisfies dependency `mlua = "^0.10"` (locked to 0.10.1) of package `clash-nyanpasu v0.1.0 (/tmp/renovate/repos/github/libnyanpasu/clash-nyanpasu/backend/tauri)`