build(deps): update lru requirement from 0.7 to 0.8 (#675)

Updates the requirements on [lru](https://github.com/jeromefroe/lru-rs) to permit the latest version.
- [Release notes](https://github.com/jeromefroe/lru-rs/releases)
- [Changelog](https://github.com/jeromefroe/lru-rs/blob/master/CHANGELOG.md)
- [Commits](jeromefroe/lru-rs@0.7.0...0.8.0)

---
updated-dependencies:
- dependency-name: lru
  dependency-type: direct:production
...

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Signed-off-by: dependabot[bot] <support@github.com>
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Co-authored-by: Andronik <write@reusable.software>

parity-util-mem/Cargo.toml

@@ -18,7 +18,7 @@ build = "build.rs"
 [dependencies]
 cfg-if = "1.0.0"
 dlmalloc = { version = "0.2.1", features = ["global"], optional = true }
-lru = { version = "0.7", optional = true }
+lru = { version = "0.8", optional = true }
 hashbrown = { version = "0.12", optional = true }
 mimalloc = { version = "0.1.18", optional = true }
 libmimalloc-sys = { version = "0.1.14", optional = true }