Bump tempfile from 3.7.1 to 3.8.0 in /src/proxy-manager (microsoft#3436)

Bumps [tempfile](https://github.com/Stebalien/tempfile) from 3.7.1 to 3.8.0.
- [Changelog](https://github.com/Stebalien/tempfile/blob/master/CHANGELOG.md)
- [Commits](Stebalien/tempfile@v3.7.1...v3.8.0)

---
updated-dependencies:
- dependency-name: tempfile
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/proxy-manager/Cargo.toml

@@ -31,4 +31,4 @@ reqwest-retry = { path = "../agent/reqwest-retry" }
 onefuzz-telemetry = { path = "../agent/onefuzz-telemetry" }
 uuid = { version = "1.4", features = ["serde"] }
 log = "0.4"
-tempfile = "3.7.0"
+tempfile = "3.8.0"