Bump lru from 0.7.5 to 0.7.6 (paritytech#701)

Bumps [lru](https://github.com/jeromefroe/lru-rs) from 0.7.5 to 0.7.6.
- [Release notes](https://github.com/jeromefroe/lru-rs/releases)
- [Changelog](https://github.com/jeromefroe/lru-rs/blob/master/CHANGELOG.md)
- [Commits](jeromefroe/lru-rs@0.7.5...0.7.6)

---
updated-dependencies:
- dependency-name: lru
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

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

client/rpc/Cargo.toml

@@ -18,7 +18,7 @@ jsonrpc-core-client = "18.0"
 jsonrpc-pubsub = "18.0"
 libsecp256k1 = "0.7"
 log = "0.4.17"
-lru = "0.7.5"
+lru = "0.7.6"
 prometheus = { version = "0.13.1", default-features = false }
 rand = "0.8"
 rlp = "0.5"