feat(fluentd): upgrade fluentd to v1.12.3

 - upgrade to fluentd v1.12.3 with latest `in_tail` fixes
 - fluent/fluentd#3355
 - fluent/fluentd#3328
 - Changelog: https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#release-v1123---20210423

Signed-off-by: Anton Ouzounov <[email protected]>

Author: Anton Ouzounov

base-image/Gemfile

@@ -1,7 +1,7 @@
 source "https://rubygems.org"
 
 # pin fluentd, probably a good idea to pin all gems
-gem "fluentd", "1.12.2"
+gem "fluentd", "~> 1.12.3"
 
 gem 'ffi', "1.14.2"
 gem 'fluent-plugin-amqp', "0.14.0"