Bump log from 0.4.7 to 0.4.8 (#5382)

Bumps [log](https://github.com/rust-lang/log) from 0.4.7 to 0.4.8.
- [Release notes](https://github.com/rust-lang/log/releases)
- [Changelog](https://github.com/rust-lang-nursery/log/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/log/commits)

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

core/Cargo.toml

@@ -37,7 +37,7 @@ jsonrpc-http-server = "13.0.0"
 jsonrpc-pubsub = "13.0.0"
 jsonrpc-ws-server = "13.0.0"
 libc = "0.2.58"
-log = "0.4.7"
+log = "0.4.8"
 memmap = { version = "0.7.0", optional = true }
 nix = "0.14.1"
 num-traits = "0.2"