Bump log from 0.4.6 to 0.4.7 (#5144)

Bumps [log](https://github.com/rust-lang/log) from 0.4.6 to 0.4.7.
- [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/compare/0.4.6...0.4.7)

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

core/Cargo.toml

@@ -34,7 +34,7 @@ jsonrpc-http-server = "12.0.0"
 jsonrpc-pubsub = "12.0.0"
 jsonrpc-ws-server = "12.0.0"
 libc = "0.2.58"
-log = "0.4.2"
+log = "0.4.7"
 memmap = { version = "0.7.0", optional = true }
 nix = "0.14.1"
 num-traits = "0.2"