Remove duplicated deprecation log entry

[alexcams]

Last change on logstash core logger config wires deprecation logger to plain logger by default. It is not needed to duplicate deprecation logs anymore because any call to deprecation_logger.deprecated() will log in plain logger output as well unless user changes this default configuration.

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[jsvd]

let's bump the patch version in the gemspec and CHANGELOG so this can be released and included in the next release of Logstash

[alexcams]

let's bump the patch version in the gemspec and CHANGELOG so this can be released and included in the next release of Logstash

@jsvd Done!