Bump version.ecs.logging from 1.5.0 to 1.6.0

Bumps `version.ecs.logging` from 1.5.0 to 1.6.0.

Updates `co.elastic.logging:log4j2-ecs-layout` from 1.5.0 to 1.6.0
- [Release notes](https://github.com/elastic/ecs-logging-java/releases)
- [Commits](elastic/ecs-logging-java@v1.5.0...v1.6.0)

Updates `co.elastic.logging:logback-ecs-encoder` from 1.5.0 to 1.6.0
- [Release notes](https://github.com/elastic/ecs-logging-java/releases)
- [Commits](elastic/ecs-logging-java@v1.5.0...v1.6.0)

Updates `co.elastic.logging:log4j-ecs-layout` from 1.5.0 to 1.6.0
- [Release notes](https://github.com/elastic/ecs-logging-java/releases)
- [Commits](elastic/ecs-logging-java@v1.5.0...v1.6.0)

Updates `co.elastic.logging:jul-ecs-formatter` from 1.5.0 to 1.6.0
- [Release notes](https://github.com/elastic/ecs-logging-java/releases)
- [Commits](elastic/ecs-logging-java@v1.5.0...v1.6.0)

Updates `co.elastic.logging:jboss-logmanager-ecs-formatter` from 1.5.0 to 1.6.0
- [Release notes](https://github.com/elastic/ecs-logging-java/releases)
- [Commits](elastic/ecs-logging-java@v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: co.elastic.logging:log4j2-ecs-layout
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: co.elastic.logging:logback-ecs-encoder
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: co.elastic.logging:log4j-ecs-layout
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: co.elastic.logging:jul-ecs-formatter
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: co.elastic.logging:jboss-logmanager-ecs-formatter
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -126,7 +126,7 @@
         (https://nvd.nist.gov/vuln/detail/CVE-2020-9488#vulnCurrentDescriptionTitle), the SMTP appender is
          excluded from the build and not packaged into the agent artifacts -->
         <version.log4j>2.12.4</version.log4j>
-        <version.ecs.logging>1.5.0</version.ecs.logging>
+        <version.ecs.logging>1.6.0</version.ecs.logging>
         <version.spring>5.0.15.RELEASE</version.spring>
         <version.jetty-server>9.4.11.v20180605</version.jetty-server>
         <version.json-schema-validator>1.3.3</version.json-schema-validator>