Bump string_cache from 0.8.3 to 0.8.4

Bumps [string_cache](https://github.com/servo/string-cache) from 0.8.3 to 0.8.4.
- [Release notes](https://github.com/servo/string-cache/releases)
- [Commits](https://github.com/servo/string-cache/compare/v0.8.3...v0.8.4)

---
updated-dependencies:
- dependency-name: string_cache
  dependency-type: indirect
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -6256,13 +6256,13 @@ dependencies = [
 
 [[package]]
 name = "string_cache"
-version = "0.8.3"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33994d0838dc2d152d17a62adf608a869b5e846b65b389af7f3dbc1de45c5b26"
+checksum = "213494b7a2b503146286049378ce02b482200519accc31872ee8be91fa820a08"
 dependencies = [
- "lazy_static",
  "new_debug_unreachable",
- "parking_lot 0.11.0",
+ "once_cell",
+ "parking_lot 0.12.0",
  "phf_shared 0.10.0",
  "precomputed-hash",
  "serde",