Bump fluentd from 1.9.2 to 1.9.3

Bumps [fluentd](https://github.com/fluent/fluentd) from 1.9.2 to 1.9.3.
- [Release notes](https://github.com/fluent/fluentd/releases)
- [Changelog](https://github.com/fluent/fluentd/blob/master/CHANGELOG.md)
- [Commits](fluent/fluentd@v1.9.2...v1.9.3)

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

Gemfile.lock

@@ -12,7 +12,7 @@ GEM
       tins (~> 1.6)
     diff-lcs (1.3)
     docile (1.3.1)
-    fluentd (1.9.2)
+    fluentd (1.9.3)
       cool.io (>= 1.4.5, < 2.0.0)
       http_parser.rb (>= 0.5.1, < 0.7.0)
       msgpack (>= 1.3.1, < 2.0.0)